Fit multiclass models for support vector machines or other classifiers
returns
a full, trained, multiclass, errorcorrecting
output codes (ECOC) model using the predictors in table Mdl
= fitcecoc(Tbl
,ResponseVarName
)Tbl
and
the class labels in Tbl.ResponseVarName
. fitcecoc
uses K(K –
1)/2 binary support vector machine (SVM) models using the oneversusone coding design, where K is
the number of unique class labels (levels). Mdl
is
a ClassificationECOC
model.
returns
an ECOC model with additional options specified by one or more Mdl
= fitcecoc(___,Name,Value
)Name,Value
pair
arguments, using any of the previous syntaxes.
For example, specify different binary learners, a different
coding design, or to crossvalidate. It is good practice to crossvalidate
using the Kfold
Name,Value
pair
argument. The crossvalidation results determine how well the model
generalizes.
[
also returns hyperparameter optimization details when you specify the
Mdl
,HyperparameterOptimizationResults
]
= fitcecoc(___,Name,Value
)OptimizeHyperparameters
namevalue pair argument and
use linear or kernel binary learners. For other Learners
,
the HyperparameterOptimizationResults
property of
Mdl
contains the results.
Train a multiclass errorcorrecting output codes (ECOC) model using support vector machine (SVM) binary learners.
Load Fisher's iris data set. Specify the predictor data X
and the response data Y
.
load fisheriris
X = meas;
Y = species;
Train a multiclass ECOC model using the default options.
Mdl = fitcecoc(X,Y)
Mdl = ClassificationECOC ResponseName: 'Y' CategoricalPredictors: [] ClassNames: {'setosa' 'versicolor' 'virginica'} ScoreTransform: 'none' BinaryLearners: {3x1 cell} CodingName: 'onevsone' Properties, Methods
Mdl
is a ClassificationECOC
model. By default, fitcecoc
uses SVM binary learners and a oneversusone coding design. You can access Mdl
properties using dot notation.
Display the class names and the coding design matrix.
Mdl.ClassNames
ans = 3x1 cell
{'setosa' }
{'versicolor'}
{'virginica' }
CodingMat = Mdl.CodingMatrix
CodingMat = 3×3
1 1 0
1 0 1
0 1 1
A oneversusone coding design for three classes yields three binary learners. The columns of CodingMat
correspond to the learners, and the rows correspond to the classes. The class order is the same as the order in Mdl.ClassNames
. For example, CodingMat(:,1)
is [1; –1; 0]
and indicates that the software trains the first SVM binary learner using all observations classified as 'setosa'
and 'versicolor'
. Because 'setosa'
corresponds to 1
, it is the positive class; 'versicolor'
corresponds to –1
, so it is the negative class.
You can access each binary learner using cell indexing and dot notation.
Mdl.BinaryLearners{1} % The first binary learner
ans = CompactClassificationSVM ResponseName: 'Y' CategoricalPredictors: [] ClassNames: [1 1] ScoreTransform: 'none' Beta: [4x1 double] Bias: 1.4492 KernelParameters: [1x1 struct] Properties, Methods
Compute the resubstitution classification error.
error = resubLoss(Mdl)
error = 0.0067
The classification error on the training data is small, but the classifier might be an overfitted model. You can crossvalidate the classifier using crossval
and compute the crossvalidation classification error instead.
Train an ECOC model composed of multiple binary, linear classification models.
Load the NLP data set.
load nlpdata
X
is a sparse matrix of predictor data, and Y
is a categorical vector of class labels. There are more than two classes in the data.
Create a default linearclassificationmodel template.
t = templateLinear();
To adjust the default values, see the NameValue Pair Arguments on templateLinear
page.
Train an ECOC model composed of multiple binary, linear classification models that can identify the product given the frequency distribution of words on a documentation web page. For faster training time, transpose the predictor data, and specify that observations correspond to columns.
X = X'; rng(1); % For reproducibility Mdl = fitcecoc(X,Y,'Learners',t,'ObservationsIn','columns')
Mdl = CompactClassificationECOC ResponseName: 'Y' ClassNames: [1x13 categorical] ScoreTransform: 'none' BinaryLearners: {78x1 cell} CodingMatrix: [13x78 double] Properties, Methods
Alternatively, you can train an ECOC model composed of default linear classification models using 'Learners','Linear'
.
To conserve memory, fitcecoc
returns trained ECOC models composed of linear classification learners in CompactClassificationECOC
model objects.
Crossvalidate an ECOC classifier with SVM binary learners, and estimate the generalized classification error.
Load Fisher's iris data set. Specify the predictor data X
and the response data Y
.
load fisheriris X = meas; Y = species; rng(1); % For reproducibility
Create an SVM template, and standardize the predictors.
t = templateSVM('Standardize',true)
t = Fit template for classification SVM. Alpha: [0x1 double] BoxConstraint: [] CacheSize: [] CachingMethod: '' ClipAlphas: [] DeltaGradientTolerance: [] Epsilon: [] GapTolerance: [] KKTTolerance: [] IterationLimit: [] KernelFunction: '' KernelScale: [] KernelOffset: [] KernelPolynomialOrder: [] NumPrint: [] Nu: [] OutlierFraction: [] RemoveDuplicates: [] ShrinkagePeriod: [] Solver: '' StandardizeData: 1 SaveSupportVectors: [] VerbosityLevel: [] Version: 2 Method: 'SVM' Type: 'classification'
t
is an SVM template. Most of the template object properties are empty. When training the ECOC classifier, the software sets the applicable properties to their default values.
Train the ECOC classifier, and specify the class order.
Mdl = fitcecoc(X,Y,'Learners',t,... 'ClassNames',{'setosa','versicolor','virginica'});
Mdl
is a ClassificationECOC
classifier. You can access its properties using dot notation.
Crossvalidate Mdl
using 10fold crossvalidation.
CVMdl = crossval(Mdl);
CVMdl
is a ClassificationPartitionedECOC
crossvalidated ECOC classifier.
Estimate the generalized classification error.
genError = kfoldLoss(CVMdl)
genError = 0.0400
The generalized classification error is 4%, which indicates that the ECOC classifier generalizes fairly well.
Train an ECOC classifier using SVM binary learners. First predict the trainingsample labels and class posterior probabilities. Then predict the maximum class posterior probability at each point in a grid. Visualize the results.
Load Fisher's iris data set. Specify the petal dimensions as the predictors and the species names as the response.
load fisheriris X = meas(:,3:4); Y = species; rng(1); % For reproducibility
Create an SVM template. Standardize the predictors, and specify the Gaussian kernel.
t = templateSVM('Standardize',true,'KernelFunction','gaussian');
t
is an SVM template. Most of its properties are empty. When the software trains the ECOC classifier, it sets the applicable properties to their default values.
Train the ECOC classifier using the SVM template. Transform classification scores to class posterior probabilities (which are returned by predict
or resubPredict
) using the 'FitPosterior'
namevalue pair argument. Specify the class order using the 'ClassNames'
namevalue pair argument. Display diagnostic messages during training by using the 'Verbose'
namevalue pair argument.
Mdl = fitcecoc(X,Y,'Learners',t,'FitPosterior',true,... 'ClassNames',{'setosa','versicolor','virginica'},... 'Verbose',2);
Training binary learner 1 (SVM) out of 3 with 50 negative and 50 positive observations. Negative class indices: 2 Positive class indices: 1 Fitting posterior probabilities for learner 1 (SVM). Training binary learner 2 (SVM) out of 3 with 50 negative and 50 positive observations. Negative class indices: 3 Positive class indices: 1 Fitting posterior probabilities for learner 2 (SVM). Training binary learner 3 (SVM) out of 3 with 50 negative and 50 positive observations. Negative class indices: 3 Positive class indices: 2 Fitting posterior probabilities for learner 3 (SVM).
Mdl
is a ClassificationECOC
model. The same SVM template applies to each binary learner, but you can adjust options for each binary learner by passing in a cell vector of templates.
Predict the trainingsample labels and class posterior probabilities. Display diagnostic messages during the computation of labels and class posterior probabilities by using the 'Verbose'
namevalue pair argument.
[label,~,~,Posterior] = resubPredict(Mdl,'Verbose',1);
Predictions from all learners have been computed. Loss for all observations has been computed. Computing posterior probabilities...
Mdl.BinaryLoss
ans = 'quadratic'
The software assigns an observation to the class that yields the smallest average binary loss. Because all binary learners are computing posterior probabilities, the binary loss function is quadratic
.
Display a random set of results.
idx = randsample(size(X,1),10,1); Mdl.ClassNames
ans = 3x1 cell
{'setosa' }
{'versicolor'}
{'virginica' }
table(Y(idx),label(idx),Posterior(idx,:),... 'VariableNames',{'TrueLabel','PredLabel','Posterior'})
ans=10×3 table
TrueLabel PredLabel Posterior
______________ ______________ ______________________________________
{'virginica' } {'virginica' } 0.0039322 0.003987 0.99208
{'virginica' } {'virginica' } 0.017067 0.018263 0.96467
{'virginica' } {'virginica' } 0.014948 0.015856 0.9692
{'versicolor'} {'versicolor'} 2.2197e14 0.87318 0.12682
{'setosa' } {'setosa' } 0.999 0.00025092 0.00074638
{'versicolor'} {'virginica' } 2.2195e14 0.05943 0.94057
{'versicolor'} {'versicolor'} 2.2194e14 0.97001 0.029985
{'setosa' } {'setosa' } 0.999 0.00024991 0.0007474
{'versicolor'} {'versicolor'} 0.0085642 0.98259 0.0088487
{'setosa' } {'setosa' } 0.999 0.00025013 0.00074717
The columns of Posterior
correspond to the class order of Mdl.ClassNames
.
Define a grid of values in the observed predictor space. Predict the posterior probabilities for each instance in the grid.
xMax = max(X); xMin = min(X); x1Pts = linspace(xMin(1),xMax(1)); x2Pts = linspace(xMin(2),xMax(2)); [x1Grid,x2Grid] = meshgrid(x1Pts,x2Pts); [~,~,~,PosteriorRegion] = predict(Mdl,[x1Grid(:),x2Grid(:)]);
For each coordinate on the grid, plot the maximum class posterior probability among all classes.
contourf(x1Grid,x2Grid,... reshape(max(PosteriorRegion,[],2),size(x1Grid,1),size(x1Grid,2))); h = colorbar; h.YLabel.String = 'Maximum posterior'; h.YLabel.FontSize = 15; hold on gh = gscatter(X(:,1),X(:,2),Y,'krk','*xd',8); gh(2).LineWidth = 2; gh(3).LineWidth = 2; title('Iris Petal Measurements and Maximum Posterior') xlabel('Petal length (cm)') ylabel('Petal width (cm)') axis tight legend(gh,'Location','NorthWest') hold off
Train a oneversusall ECOC classifier using a GentleBoost
ensemble of decision trees with surrogate splits. To speed up training, bin numeric predictors and use parallel computing. Binning is valid only when fitcecoc
uses a tree learner. After training, estimate the classification error using 10fold crossvalidation. Note that parallel computing requires Parallel Computing Toolbox™.
Load Sample Data
Load and inspect the arrhythmia
data set.
load arrhythmia
[n,p] = size(X)
n = 452
p = 279
isLabels = unique(Y); nLabels = numel(isLabels)
nLabels = 13
tabulate(categorical(Y))
Value Count Percent 1 245 54.20% 2 44 9.73% 3 15 3.32% 4 15 3.32% 5 13 2.88% 6 25 5.53% 7 3 0.66% 8 2 0.44% 9 9 1.99% 10 50 11.06% 14 4 0.88% 15 5 1.11% 16 22 4.87%
The data set contains 279
predictors, and the sample size of 452
is relatively small. Of the 16 distinct labels, only 13 are represented in the response (Y
). Each label describes various degrees of arrhythmia, and 54.20% of the observations are in class 1
.
Train OneVersusAll ECOC Classifier
Create an ensemble template. You must specify at least three arguments: a method, a number of learners, and the type of learner. For this example, specify 'GentleBoost'
for the method, 100
for the number of learners, and a decision tree template that uses surrogate splits because there are missing observations.
tTree = templateTree('surrogate','on'); tEnsemble = templateEnsemble('GentleBoost',100,tTree);
tEnsemble
is a template object. Most of its properties are empty, but the software fills them with their default values during training.
Train a oneversusall ECOC classifier using the ensembles of decision trees as binary learners. To speed up training, use binning and parallel computing.
Binning ('NumBins',50
) — When you have a large training data set, you can speed up training (a potential decrease in accuracy) by using the 'NumBins'
namevalue pair argument. This argument is valid only when fitcecoc
uses a tree learner. If you specify the 'NumBins'
value, then the software bins every numeric predictor into a specified number of equiprobable bins, and then grows trees on the bin indices instead of the original data. You can try 'NumBins',50
first, and then change the 'NumBins'
value depending on the accuracy and training speed.
Parallel computing ('Options',statset('UseParallel',true)
) — With a Parallel Computing Toolbox license, you can speed up the computation by using parallel computing, which sends each binary learner to a worker in the pool. The number of workers depends on your system configuration. When you use decision trees for binary learners, fitcecoc
parallelizes training using Intel® Threading Building Blocks (TBB) for dualcore systems and above. Therefore, specifying the 'UseParallel'
option is not helpful on a single computer. Use this option on a cluster.
Additionally, specify that the prior probabilities are 1/K, where K = 13 is the number of distinct classes.
options = statset('UseParallel',true); Mdl = fitcecoc(X,Y,'Coding','onevsall','Learners',tEnsemble,... 'Prior','uniform','NumBins',50,'Options',options);
Starting parallel pool (parpool) using the 'local' profile ... Connected to the parallel pool (number of workers: 6).
Mdl
is a ClassificationECOC
model.
CrossValidation
Crossvalidate the ECOC classifier using 10fold crossvalidation.
CVMdl = crossval(Mdl,'Options',options);
Warning: One or more folds do not contain points from all the groups.
CVMdl
is a ClassificationPartitionedECOC
model. The warning indicates that some classes are not represented while the software trains at least one fold. Therefore, those folds cannot predict labels for the missing classes. You can inspect the results of a fold using cell indexing and dot notation. For example, access the results of the first fold by entering CVMdl.Trained{1}
.
Use the crossvalidated ECOC classifier to predict validationfold labels. You can compute the confusion matrix by using confusionchart
. Move and resize the chart by changing the inner position property to ensure that the percentages appear in the row summary.
oofLabel = kfoldPredict(CVMdl,'Options',options); ConfMat = confusionchart(Y,oofLabel,'RowSummary','totalnormalized'); ConfMat.InnerPosition = [0.10 0.12 0.85 0.85];
Reproduce Binned Data
Reproduce binned predictor data by using the BinEdges
property of the trained model and the discretize
function.
X = Mdl.X; % Predictor data Xbinned = zeros(size(X)); edges = Mdl.BinEdges; % Find indices of binned predictors. idxNumeric = find(~cellfun(@isempty,edges)); if iscolumn(idxNumeric) idxNumeric = idxNumeric'; end for j = idxNumeric x = X(:,j); % Convert x to array if x is a table. if istable(x) x = table2array(x); end % Group x into bins by using the discretize function. xbinned = discretize(x,[inf; edges{j}; inf]); Xbinned(:,j) = xbinned; end
Xbinned
contains the bin indices, ranging from 1 to the number of bins, for numeric predictors. Xbinned
values are 0
for categorical predictors. If X
contains NaN
s, then the corresponding Xbinned
values are NaN
s.
Optimize hyperparameters automatically using fitcecoc
.
Load the fisheriris
data set.
load fisheriris
X = meas;
Y = species;
Find hyperparameters that minimize fivefold crossvalidation loss by using automatic hyperparameter optimization. For reproducibility, set the random seed and use the 'expectedimprovementplus'
acquisition function.
rng default Mdl = fitcecoc(X,Y,'OptimizeHyperparameters','auto',... 'HyperparameterOptimizationOptions',struct('AcquisitionFunctionName',... 'expectedimprovementplus'))
====================================================================================================================  Iter  Eval  Objective  Objective  BestSoFar  BestSoFar  Coding  BoxConstraint KernelScale    result   runtime  (observed)  (estim.)     ====================================================================================================================  1  Best  0.10667  1.6471  0.10667  0.10667  onevsone  5.6939  200.36 
 2  Best  0.066667  3.3008  0.066667  0.068735  onevsone  94.849  0.0032549 
 3  Accept  0.08  0.48469  0.066667  0.066837  onevsall  0.01378  0.076021 
 4  Accept  0.08  0.30655  0.066667  0.066676  onevsall  889  38.798 
 5  Best  0.04  0.39375  0.04  0.040502  onevsone  0.021561  0.01569 
 6  Accept  0.04  0.37592  0.04  0.039999  onevsone  0.48338  0.02941 
 7  Accept  0.04  0.30231  0.04  0.039989  onevsone  305.45  0.18647 
 8  Best  0.026667  0.67769  0.026667  0.026674  onevsone  0.0010168  0.10757 
 9  Accept  0.086667  0.30823  0.026667  0.026669  onevsone  0.001007  0.3275 
 10  Accept  0.046667  1.366  0.026667  0.026673  onevsone  736.18  0.071026 
 11  Accept  0.04  0.45032  0.026667  0.035679  onevsone  35.928  0.13079 
 12  Accept  0.033333  0.44963  0.026667  0.030065  onevsone  0.0017593  0.11245 
 13  Accept  0.026667  0.60534  0.026667  0.026544  onevsone  0.0011306  0.062222 
 14  Accept  0.026667  0.59201  0.026667  0.026089  onevsone  0.0011124  0.079161 
 15  Accept  0.026667  0.32808  0.026667  0.026184  onevsone  0.0014395  0.073096 
 16  Best  0.02  0.31449  0.02  0.021144  onevsone  0.0010299  0.035054 
 17  Accept  0.02  0.38129  0.02  0.020431  onevsone  0.0010379  0.03138 
 18  Accept  0.033333  0.28562  0.02  0.024292  onevsone  0.0011889  0.02915 
 19  Accept  0.02  0.32346  0.02  0.022327  onevsone  0.0011336  0.042445 
 20  Best  0.013333  0.61854  0.013333  0.020178  onevsone  0.0010854  0.048345 
====================================================================================================================  Iter  Eval  Objective  Objective  BestSoFar  BestSoFar  Coding  BoxConstraint KernelScale    result   runtime  (observed)  (estim.)     ====================================================================================================================  21  Accept  0.5  12.496  0.013333  0.020718  onevsall  689.42  0.001007 
 22  Accept  0.33333  0.52657  0.013333  0.018299  onevsall  0.0011091  1.2155 
 23  Accept  0.33333  0.83188  0.013333  0.017851  onevsall  529.11  372.18 
 24  Accept  0.04  0.3554  0.013333  0.017879  onevsone  853.41  22.141 
 25  Accept  0.046667  0.29602  0.013333  0.018114  onevsone  744.03  6.3339 
 26  Accept  0.10667  0.42862  0.013333  0.018226  onevsone  0.0010775  999.54 
 27  Accept  0.04  0.46833  0.013333  0.018557  onevsone  0.0020893  0.001005 
 28  Accept  0.10667  0.61122  0.013333  0.019634  onevsone  0.0010666  12.404 
 29  Accept  0.32  12.527  0.013333  0.018352  onevsall  951.6  0.027202 
 30  Accept  0.04  0.30569  0.013333  0.018597  onevsone  936.87  1.7813 
__________________________________________________________ Optimization completed. MaxObjectiveEvaluations of 30 reached. Total function evaluations: 30 Total elapsed time: 80.4186 seconds Total objective function evaluation time: 42.3589 Best observed feasible point: Coding BoxConstraint KernelScale ________ _____________ ___________ onevsone 0.0010854 0.048345 Observed objective function value = 0.013333 Estimated objective function value = 0.018594 Function evaluation time = 0.61854 Best estimated feasible point (according to models): Coding BoxConstraint KernelScale ________ _____________ ___________ onevsone 0.0011336 0.042445 Estimated objective function value = 0.018597 Estimated function evaluation time = 0.41319
Mdl = ClassificationECOC ResponseName: 'Y' CategoricalPredictors: [] ClassNames: {'setosa' 'versicolor' 'virginica'} ScoreTransform: 'none' BinaryLearners: {3x1 cell} CodingName: 'onevsone' HyperparameterOptimizationResults: [1x1 BayesianOptimization] Properties, Methods
Create two multiclass ECOC models trained on tall data. Use linear binary learners for one of the models and kernel binary learners for the other. Compare the resubstitution classification error of the two models.
In general, you can perform multiclass classification of tall data by using fitcecoc
with linear or kernel binary learners. When you use fitcecoc
to train a model on tall arrays, you cannot use SVM binary learners directly. However, you can use either linear or kernel binary classification models that use SVMs.
When you perform calculations on tall arrays, MATLAB® uses either a parallel pool (default if you have Parallel Computing Toolbox™) or the local MATLAB session. If you want to run the example using the local MATLAB session when you have Parallel Computing Toolbox, you can change the global execution environment by using the mapreducer
function.
Create a datastore that references the folder containing Fisher's iris data set. Specify 'NA'
values as missing data so that datastore
replaces them with NaN
values. Create tall versions of the predictor and response data.
ds = datastore('fisheriris.csv','TreatAsMissing','NA'); t = tall(ds);
Starting parallel pool (parpool) using the 'local' profile ... Connected to the parallel pool (number of workers: 6).
X = [t.SepalLength t.SepalWidth t.PetalLength t.PetalWidth]; Y = t.Species;
Standardize the predictor data.
Z = zscore(X);
Train a multiclass ECOC model that uses tall data and linear binary learners. By default, when you pass tall arrays to fitcecoc
, the software trains linear binary learners that use SVMs. Because the response data contains only three unique classes, change the coding scheme from oneversusall (which is the default when you use tall data) to oneversusone (which is the default when you use inmemory data).
For reproducibility, set the seeds of the random number generators using rng
and tallrng
. The results can vary depending on the number of workers and the execution environment for the tall arrays. For details, see Control Where Your Code Runs.
rng('default') tallrng('default') mdlLinear = fitcecoc(Z,Y,'Coding','onevsone')
Training binary learner 1 (Linear) out of 3. Training binary learner 2 (Linear) out of 3. Training binary learner 3 (Linear) out of 3.
mdlLinear = CompactClassificationECOC ResponseName: 'Y' ClassNames: {'setosa' 'versicolor' 'virginica'} ScoreTransform: 'none' BinaryLearners: {3×1 cell} CodingMatrix: [3×3 double] Properties, Methods
mdlLinear
is a CompactClassificationECOC
model composed of three binary learners.
Train a multiclass ECOC model that uses tall data and kernel binary learners. First, create a templateKernel
object to specify the properties of the kernel binary learners; in particular, increase the number of expansion dimensions to $${2}^{16}$$.
tKernel = templateKernel('NumExpansionDimensions',2^16)
tKernel = Fit template for classification Kernel. BetaTolerance: [] BlockSize: [] BoxConstraint: [] Epsilon: [] NumExpansionDimensions: 65536 GradientTolerance: [] HessianHistorySize: [] IterationLimit: [] KernelScale: [] Lambda: [] Learner: 'svm' LossFunction: [] Stream: [] VerbosityLevel: [] Version: 1 Method: 'Kernel' Type: 'classification'
By default, the kernel binary learners use SVMs.
Pass the templateKernel
object to fitcecoc
and change the coding scheme to oneversusone.
mdlKernel = fitcecoc(Z,Y,'Learners',tKernel,'Coding','onevsone')
Training binary learner 1 (Kernel) out of 3. Training binary learner 2 (Kernel) out of 3. Training binary learner 3 (Kernel) out of 3.
mdlKernel = CompactClassificationECOC ResponseName: 'Y' ClassNames: {'setosa' 'versicolor' 'virginica'} ScoreTransform: 'none' BinaryLearners: {3×1 cell} CodingMatrix: [3×3 double] Properties, Methods
mdlKernel
is also a CompactClassificationECOC
model composed of three binary learners.
Compare the resubstitution classification error of the two models.
errorLinear = gather(loss(mdlLinear,Z,Y))
Evaluating tall expression using the Parallel Pool 'local':  Pass 1 of 1: Completed in 1.4 sec Evaluation completed in 1.6 sec
errorLinear = 0.0333
errorKernel = gather(loss(mdlKernel,Z,Y))
Evaluating tall expression using the Parallel Pool 'local':  Pass 1 of 1: Completed in 15 sec Evaluation completed in 16 sec
errorKernel = 0.0067
mdlKernel
misclassifies a smaller percentage of the training data than mdlLinear
.
Tbl
— Sample dataSample data, specified as a table. Each row of Tbl
corresponds
to one observation, and each column corresponds to one predictor.
Optionally, Tbl
can contain one additional column
for the response variable. Multicolumn variables and cell arrays other
than cell arrays of character vectors are not accepted.
If Tbl
contains the response variable, and
you want to use all remaining variables in Tbl
as
predictors, then specify the response variable using ResponseVarName
.
If Tbl
contains the response variable, and
you want to use only a subset of the remaining variables in Tbl
as
predictors, specify a formula using formula
.
If Tbl
does not contain the response variable,
specify a response variable using Y
. The length
of response variable and the number of Tbl
rows
must be equal.
Data Types: table
ResponseVarName
— Response variable nameTbl
Response variable name, specified as the name of a variable in
Tbl
.
You must specify ResponseVarName
as a character vector or string scalar.
For example, if the response variable Y
is
stored as Tbl.Y
, then specify it as
'Y'
. Otherwise, the software
treats all columns of Tbl
, including
Y
, as predictors when training
the model.
The response variable must be a categorical, character, or string array, a logical or numeric
vector, or a cell array of character vectors. If
Y
is a character array, then each
element of the response variable must correspond to one row of
the array.
A good practice is to specify the order of the classes by using the
ClassNames
namevalue pair
argument.
Data Types: char
 string
formula
— Explanatory model of response variable and subset of predictor variablesExplanatory model of the response variable and a subset of the predictor variables,
specified as a character vector or string scalar in the form
'Y~X1+X2+X3'
. In this form, Y
represents the
response variable, and X1
, X2
, and
X3
represent the predictor variables.
To specify a subset of variables in Tbl
as predictors for
training the model, use a formula. If you specify a formula, then the software does not
use any variables in Tbl
that do not appear in
formula
.
The variable names in the formula must be both variable names in Tbl
(Tbl.Properties.VariableNames
) and valid MATLAB^{®} identifiers.
You can verify the variable names in Tbl
by using the isvarname
function. The following code returns logical 1
(true
) for each variable that has a valid variable name.
cellfun(@isvarname,Tbl.Properties.VariableNames)
Tbl
are not valid, then convert them by using the
matlab.lang.makeValidName
function.Tbl.Properties.VariableNames = matlab.lang.makeValidName(Tbl.Properties.VariableNames);
Data Types: char
 string
Y
— Class labelsClass labels to which the ECOC model is trained, specified as a categorical, character, or string array, logical or numeric vector, or cell array of character vectors.
If Y
is a character array, then each element
must correspond to one row of the array.
The length of Y
and the number of rows of Tbl
or X
must
be equal.
It is good practice to specify the class order using the ClassNames
namevalue
pair argument.
Data Types: categorical
 char
 string
 logical
 single
 double
 cell
X
— Predictor dataPredictor data, specified as a full or sparse matrix.
The length of Y
and the number of observations
in X
must be equal.
To specify the names of the predictors in the order of their
appearance in X
, use the PredictorNames
namevalue
pair argument.
Note
For linear classification learners, if you orient X
so
that observations correspond to columns and specify 'ObservationsIn','columns'
,
then you can experience a significant reduction in optimizationexecution
time.
For all other learners, orient X
so
that observations correspond to rows.
fitcecoc
supports sparse matrices
for training linear classification models only.
Data Types: double
 single
Note
The software treats NaN
, empty character vector
(''
), empty string (""
),
<missing>
, and <undefined>
elements as missing data. The software removes rows of X
corresponding to missing values in Y
. However, the treatment of
missing values in X
varies among binary learners. For details,
see the training functions for your binary learners: fitcdiscr
, fitckernel
, fitcknn
, fitclinear
, fitcnb
, fitcsvm
, fitctree
, or fitcensemble
. Removing observations decreases the effective training
or crossvalidation sample size.
Specify optional
commaseparated pairs of Name,Value
arguments. Name
is
the argument name and Value
is the corresponding value.
Name
must appear inside quotes. You can specify several name and value
pair arguments in any order as
Name1,Value1,...,NameN,ValueN
.
'Learners','tree','Coding','onevsone','CrossVal','on'
specifies to use decision trees for all binary learners, a oneversusone coding
design, and to implement 10fold crossvalidation.Note
You cannot use any crossvalidation namevalue pair argument along with the
'OptimizeHyperparameters'
namevalue pair argument. You can modify
the crossvalidation for 'OptimizeHyperparameters'
only by using the
'HyperparameterOptimizationOptions'
namevalue pair
argument.
'Coding'
— Coding design'onevsone'
(default)  'allpairs'
 'binarycomplete'
 'denserandom'
 'onevsall'
 'ordinal'
 'sparserandom'
 'ternarycomplete'
 numeric matrixCoding design name, specified as the commaseparated pair consisting
of 'Coding'
and a numeric matrix or a value in
this table.
Value  Number of Binary Learners  Description 

'allpairs' and 'onevsone'  K(K – 1)/2  For each binary learner, one class is positive, another is negative, and the software ignores the rest. This design exhausts all combinations of class pair assignments. 
'binarycomplete'  $${2}^{(K1)}1$$  This design partitions the classes into all binary combinations,
and does not ignore any classes. For each binary learner, all class
assignments are 1 and 1 with
at least one positive and negative class in the assignment. 
'denserandom'  Random, but approximately 10 log_{2}K  For each binary learner, the software randomly assigns classes into positive or negative classes, with at least one of each type. For more details, see Random Coding Design Matrices. 
'onevsall'  K  For each binary learner, one class is positive and the rest are negative. This design exhausts all combinations of positive class assignments. 
'ordinal'  K – 1  For the first binary learner, the first class is negative, and the rest positive. For the second binary learner, the first two classes are negative, the rest positive, and so on. 
'sparserandom'  Random, but approximately 15 log_{2}K  For each binary learner, the software randomly assigns classes as positive or negative with probability 0.25 for each, and ignores classes with probability 0.5. For more details, see Random Coding Design Matrices. 
'ternarycomplete'  $$\left({3}^{K}{2}^{(K+1)}+1\right)/2$$  This design partitions the classes into all ternary combinations.
All class assignments are 0 , 1 ,
and 1 with at least one positive and one negative
class in the assignment. 
You can also specify a coding design using a custom coding matrix. The custom coding matrix is
a KbyL matrix. Each row corresponds to a class
and each column corresponds to a binary learner. The class order (rows) corresponds to
the order in ClassNames
. Compose the
matrix by following these guidelines:
Every element of the custom coding matrix must be 1
,
0
, or 1
, and the value must
correspond to a dichotomous class assignment. This table describes the
meaning of Coding(i,j)
, that is, the class that learner
j
assigns to observations in class
i
.
Value  Dichotomous Class Assignment 

–1  Learner j assigns observations in class i to a negative
class. 
0  Before training, learner j removes observations
in class i from the data set. 
1  Learner j assigns observations in class i to a positive
class. 
Every column must contain at least one 1
or
1
.
For all column indices i
,j
such that
i
≠ j
,
Coding(:,i)
cannot equal
Coding(:,j)
and Coding(:,i)
cannot
equal Coding(:,j)
.
All rows of the custom coding matrix must be different.
For more details on the form of custom coding design matrices, see Custom Coding Design Matrices.
Example: 'Coding','ternarycomplete'
Data Types: char
 string
 double
 single
 int16
 int32
 int64
 int8
'FitPosterior'
— Flag indicating whether to transform scores to posterior probabilitiesfalse
or 0
(default)  true
or 1
Flag indicating whether to transform scores to posterior probabilities,
specified as the commaseparated pair consisting of 'FitPosterior'
and
a true
(1
) or false
(0
).
If FitPosterior
is true
,
then the software transforms binarylearner classification scores
to posterior probabilities. You can obtain posterior probabilities
by using kfoldPredict
, predict
,
or resubPredict
.
fitcecoc
does not support fitting posterior probabilities if:
The ensemble method is AdaBoostM2
,
LPBoost
, RUSBoost
,
RobustBoost
, or TotalBoost
.
The binary learners (Learners
) are linear or kernel
classification models that implement SVM. To obtain posterior probabilities
for linear or kernel classification models, implement logistic regression
instead.
Example: 'FitPosterior',true
Data Types: logical
'Learners'
— Binary learner templates'svm'
(default)  'discriminant'
 'kernel'
 'knn'
 'linear'
 'naivebayes'
 'tree'
 template object  cell vector of template objectsBinary learner templates, specified as the commaseparated pair consisting of
'Learners'
and a character vector, string scalar, template
object, or cell vector of template objects. Specifically, you can specify binary
classifiers such as SVM, and the ensembles that use GentleBoost
,
LogitBoost
, and RobustBoost
, to solve
multiclass problems. However, fitcecoc
also supports multiclass
models as binary classifiers.
If Learners
is a character vector or string scalar, then the software
trains each binary learner using the default values of the specified
algorithm. This table summarizes the available algorithms.
Value  Description 

'discriminant'  Discriminant analysis. For default options, see
templateDiscriminant . 
'kernel'  Kernel classification model. For default options, see
templateKernel . 
'knn'  knearest neighbors. For default
options, see templateKNN . 
'linear'  Linear classification model. For default options, see
templateLinear . 
'naivebayes'  Naive Bayes. For default options, see templateNaiveBayes . 
'svm'  SVM. For default options, see templateSVM . 
'tree'  Classification trees. For default options, see
templateTree . 
If Learners
is a template object,
then each binary learner trains according to the stored options. You
can create a template object using:
templateDiscriminant
,
for discriminant analysis.
templateEnsemble
, for ensemble learning. You
must at least specify the learning method (Method
), the number of learners (NLearn
), and
the type of learner (Learners
).
You cannot use the AdaBoostM2
ensemble method
for binary learning.
templateKernel
, for kernel
classification.
templateKNN
,
for knearest neighbors.
templateLinear
,
for linear classification.
templateNaiveBayes
,
for naive Bayes.
templateSVM
,
for SVM.
templateTree
,
for classification trees.
If Learners
is a cell vector of template objects, then:
Cell j corresponds to binary learner
j (in other words, column
j of the coding design matrix), and the
cell vector must have length L.
L is the number of columns in the coding
design matrix. For details, see
Coding
.
To use one of the builtin loss functions for prediction, then
all binary learners must return a score in the same range. For
example, you cannot include default SVM binary learners with
default naive Bayes binary learners. The former returns a score
in the range (∞,∞), and the latter returns a
posterior probability as a score. Otherwise, you must provide a
custom loss as a function handle to functions such as predict
and loss
.
You cannot specify linear classification model learner templates with any other template.
Similarly, you cannot specify kernel classification model learner templates with any other template.
By default, the software trains learners using default SVM templates.
Example: 'Learners','tree'
'NumBins'
— Number of bins for numeric predictors[]
(empty) (default)  positive integer scalarNumber of bins for numeric predictors, specified as the
commaseparated pair consisting of 'NumBins'
and a
positive integer scalar. This argument is valid only when
fitcecoc
uses a tree learner, that is,
'Learners'
is either 'tree'
or a template object created by using templateTree
, or a template
object created by using templateEnsemble
with tree
weak learners.
If the 'NumBins'
value is empty (default), then the software
does not bin any predictors.
If you specify the 'NumBins'
value as a positive integer
scalar, then the software bins every numeric predictor into a specified number of
equiprobable bins, and then grows trees on the bin indices instead of the original data.
If the 'NumBins'
value exceeds the number
(u) of unique values for a predictor, then
fitcecoc
bins the predictor into
u bins.
fitcecoc
does not bin categorical
predictors.
When you use a large training data set, this binning option speeds up training but causes a
potential decrease in accuracy. You can try 'NumBins',50
first, and then
change the 'NumBins'
value depending on the accuracy and training
speed.
A trained model stores the bin edges in the BinEdges
property.
Example: 'NumBins',50
Data Types: single
 double
'NumConcurrent'
— Number of binary learners concurrently trained1
(default)  positive integer scalarNumber of binary learners concurrently trained, specified as the
commaseparated pair consisting of 'NumConcurrent'
and a positive integer scalar. The default value is
1
, which means fitcecoc
trains
the binary learners sequentially.
Note
This option applies only when you use
fitcecoc
on tall arrays. See Tall Arrays
for more information.
Data Types: single
 double
'ObservationsIn'
— Predictor data observation dimension'rows'
(default)  'columns'
Predictor data observation dimension, specified as the commaseparated
pair consisting of 'ObservationsIn'
and
'columns'
or 'rows'
.
Note
For linear classification learners, if you orient
X
so that observations correspond to
columns and specify
'ObservationsIn','columns'
, then you
can experience a significant reduction in
optimizationexecution time.
For all other learners, orient X
so
that observations correspond to rows.
Example: 'ObservationsIn','columns'
'Verbose'
— Verbosity level0
(default)  1
 2
Verbosity level, specified as the commaseparated pair consisting of
'Verbose'
and 0
,
1
, or 2
.
Verbose
controls the amount of diagnostic
information per binary learner that the software displays in the Command
Window.
This table summarizes the available verbosity level options.
Value  Description 

0  The software does not display diagnostic information. 
1  The software displays diagnostic messages every time it trains a new binary learner. 
2  The software displays extra diagnostic messages every time it trains a new binary learner. 
Each binary learner has its own verbosity level that is independent of
this namevalue pair argument. To change the verbosity level of a binary
learner, create a template object and specify the
'Verbose'
namevalue pair argument. Then, pass
the template object to fitcecoc
by using the
'Learners'
namevalue pair argument.
Example: 'Verbose',1
Data Types: double
 single
'CrossVal'
— Flag to train crossvalidated classifier'off'
(default)  'on'
Flag to train a crossvalidated classifier, specified as the
commaseparated pair consisting of 'Crossval'
and
'on'
or 'off'
.
If you specify 'on'
, then the software trains a
crossvalidated classifier with 10 folds.
You can override this crossvalidation setting using one of the
CVPartition
, Holdout
,
KFold
, or Leaveout
namevalue pair arguments. You can only use one crossvalidation
namevalue pair argument at a time to create a crossvalidated
model.
Alternatively, crossvalidate later by passing
Mdl
to crossval
.
Example: 'Crossval','on'
'CVPartition'
— Crossvalidation partition[]
(default)  cvpartition
partition objectCrossvalidation partition, specified as the commaseparated pair consisting of
'CVPartition'
and a cvpartition
partition
object created by cvpartition
. The partition object
specifies the type of crossvalidation and the indexing for the training and validation
sets.
To create a crossvalidated model, you can use one of these four namevalue pair arguments
only: CVPartition
, Holdout
,
KFold
, or Leaveout
.
Example: Suppose you create a random partition for 5fold crossvalidation on 500
observations by using cvp = cvpartition(500,'KFold',5)
. Then, you can
specify the crossvalidated model by using
'CVPartition',cvp
.
'Holdout'
— Fraction of data for holdout validationFraction of the data used for holdout validation, specified as the commaseparated pair
consisting of 'Holdout'
and a scalar value in the range (0,1). If you
specify 'Holdout',p
, then the software completes these steps:
Randomly select and reserve p*100
% of the data as
validation data, and train the model using the rest of the data.
Store the compact, trained model in the Trained
property of the crossvalidated model.
To create a crossvalidated model, you can use one of these
four namevalue pair arguments only: CVPartition
, Holdout
, KFold
,
or Leaveout
.
Example: 'Holdout',0.1
Data Types: double
 single
'KFold'
— Number of folds10
(default)  positive integer value greater than 1Number of folds to use in a crossvalidated model, specified as the commaseparated pair
consisting of 'KFold'
and a positive integer value greater than 1. If
you specify 'KFold',k
, then the software completes these steps:
Randomly partition the data into k
sets.
For each set, reserve the set as validation data, and train the model
using the other k
– 1 sets.
Store the k
compact, trained models in the cells of a
k
by1 cell vector in the Trained
property of the crossvalidated model.
To create a crossvalidated model, you can use one of these
four namevalue pair arguments only: CVPartition
, Holdout
, KFold
,
or Leaveout
.
Example: 'KFold',5
Data Types: single
 double
'Leaveout'
— Leaveoneout crossvalidation flag'off'
(default)  'on'
Leaveoneout crossvalidation flag, specified as the commaseparated
pair consisting of 'Leaveout'
and
'on'
or 'off'
. If you specify
'Leaveout','on'
, then, for each of the
n observations, where n is
size(Mdl.X,1)
, the software:
Reserves the observation as validation data, and trains the model using the other n – 1 observations
Stores the n compact, trained models in
the cells of a nby1 cell vector in the
Trained
property of the
crossvalidated model.
To create a crossvalidated model, you can use one of these four
options only: CVPartition
,
Holdout
, KFold
, or
Leaveout
.
Note
Leaveoneout is not recommended for crossvalidating ECOC models composed of linear or kernel classification model learners.
Example: 'Leaveout','on'
'CategoricalPredictors'
— Categorical predictors list'all'
Categorical predictors
list, specified as the commaseparated pair consisting of
'CategoricalPredictors'
and one of the values in this table.
Value  Description 

Vector of positive integers  Each entry in the vector is an index value corresponding to the column of the
predictor data (X or Tbl ) that contains a
categorical variable. 
Logical vector  A true entry means that the corresponding column of predictor
data (X or Tbl ) is a categorical
variable. 
Character matrix  Each row of the matrix is the name of a predictor variable. The names must match
the entries in PredictorNames . Pad the names with extra blanks so
each row of the character matrix has the same length. 
String array or cell array of character vectors  Each element in the array is the name of a predictor variable. The names must match
the entries in PredictorNames . 
'all'  All predictors are categorical. 
Specification of 'CategoricalPredictors'
is
appropriate if:
At least one predictor is categorical and all binary learners are classification trees, naive Bayes learners, SVMs, linear learners, kernel learners, or ensembles of classification trees.
All predictors are categorical and at least one binary learner is kNN.
If you specify 'CategoricalPredictors'
for any other learner, then the software warns that it cannot train that
binary learner. For example, the software cannot train discriminant
analysis classifiers using categorical predictors.
Each learner identifies and treats categorical predictors in the same
way as the fitting function corresponding to the learner. See 'CategoricalPredictors'
of
fitckernel
for kernel learners, 'CategoricalPredictors'
of fitcknn
for knearest learners, 'CategoricalPredictors'
of
fitclinear
for linear learners, 'CategoricalPredictors'
of fitcnb
for naive Bayes learners, 'CategoricalPredictors'
of fitcsvm
for SVM learners, and 'CategoricalPredictors'
of fitctree
for tree learners.
Example: 'CategoricalPredictors','all'
Data Types: single
 double
 logical
 char
 string
 cell
'ClassNames'
— Names of classes to use for trainingNames of classes to use for training, specified as the commaseparated pair consisting of
'ClassNames'
and a categorical, character, or string array, a
logical or numeric vector, or a cell array of character vectors.
ClassNames
must have the same data type as
Y
.
If ClassNames
is a character array, then each element must correspond to
one row of the array.
Use 'ClassNames'
to:
Order the classes during training.
Specify the order of any input or output argument dimension that
corresponds to the class order. For example, use
'ClassNames'
to specify the order of the dimensions
of Cost
or the column order of classification scores
returned by predict
.
Select a subset of classes for training. For example, suppose that the set
of all distinct class names in Y
is
{'a','b','c'}
. To train the model using observations
from classes 'a'
and 'c'
only, specify
'ClassNames',{'a','c'}
.
The default value for ClassNames
is the set of all distinct class names in
Y
.
Example: 'ClassNames',{'b','g'}
Data Types: categorical
 char
 string
 logical
 single
 double
 cell
'Cost'
— Misclassification costMisclassification cost, specified as the commaseparated pair
consisting of 'Cost'
and a square matrix or
structure. If you specify:
The square matrix Cost
, then
Cost(i,j)
is the cost of classifying a
point into class j
if its true class is
i
. That is, the rows correspond to the
true class and the columns correspond to the predicted class. To
specify the class order for the corresponding rows and columns
of Cost
, additionally specify the
ClassNames
namevalue pair
argument.
The structure S
, then it must have two fields:
S.ClassNames
, which contains
the class names as a variable of the same data type
as Y
S.ClassificationCosts
, which
contains the cost matrix with rows and columns
ordered as in S.ClassNames
The default is ones(
, where
K
) 
eye(K
)K
is the number of distinct
classes.
Example: 'Cost',[0 1 2 ; 1 0 2; 2 2
0]
Data Types: double
 single
 struct
'Options'
— Parallel computing options[]
(default)  structure array returned by statset
Parallel computing options, specified as the commaseparated
pair consisting of 'Options'
and a structure array
returned by statset
. These options
require Parallel Computing Toolbox™. fitcecoc
uses 'Streams'
, 'UseParallel'
,
and 'UseSubtreams'
fields.
This table summarizes the available options.
Option  Description 

'Streams' 
A
In that case, use a cell array of the same size as the
parallel pool. If a parallel pool is not open, then the software
tries to open one (depending on your preferences), and

'UseParallel'  If you have Parallel Computing Toolbox, then you can invoke a
pool of workers by setting
When you use
decision trees for binary learners,

'UseSubstreams'  Set to true to compute in parallel using
the stream specified by 'Streams' . Default is false .
For example, set Streams to a type allowing substreams,
such as'mlfg6331_64' or 'mrg32k3a' . 
A best practice to ensure more
predictable results is to use parpool
(Parallel Computing Toolbox) and
explicitly create a parallel pool before you invoke parallel computing
using fitcecoc
.
Example: 'Options',statset('UseParallel',true)
Data Types: struct
'PredictorNames'
— Predictor variable namesPredictor variable names, specified as the commaseparated pair consisting of
'PredictorNames'
and a string array of unique names or cell array
of unique character vectors. The functionality of 'PredictorNames'
depends on the way you supply the training data.
If you supply X
and Y
, then you
can use 'PredictorNames'
to assign names to the predictor
variables in X
.
The order of the names in PredictorNames
must correspond to the column order of X
.
That is, PredictorNames{1}
is the name of
X(:,1)
,
PredictorNames{2}
is the name of
X(:,2)
, and so on. Also,
size(X,2)
and
numel(PredictorNames)
must be
equal.
By default, PredictorNames
is
{'x1','x2',...}
.
If you supply Tbl
, then you can use
'PredictorNames'
to choose which predictor variables
to use in training. That is, fitcecoc
uses only the
predictor variables in PredictorNames
and the response
variable during training.
PredictorNames
must be a subset of
Tbl.Properties.VariableNames
and cannot
include the name of the response variable.
By default, PredictorNames
contains the
names of all predictor variables.
A good practice is to specify the predictors for training
using either 'PredictorNames'
or
formula
, but not both.
Example: 'PredictorNames',{'SepalLength','SepalWidth','PetalLength','PetalWidth'}
Data Types: string
 cell
'Prior'
— Prior probabilities'empirical'
(default)  'uniform'
 numeric vector  structure arrayPrior probabilities for each class, specified as the commaseparated
pair consisting of 'Prior'
and a value in this
table.
Value  Description 

'empirical'  The class prior probabilities are the class
relative frequencies in
Y . 
'uniform'  All class prior probabilities are equal to 1/K, where K is the number of classes. 
numeric vector  Each element is a class prior probability. Order
the elements according to
Mdl .ClassNames
or specify the order using the
ClassNames namevalue pair
argument. The software normalizes the elements such
that they sum to 1 . 
structure 
A structure

For more details on how the software incorporates class prior probabilities, see Prior Probabilities and Cost.
Example: struct('ClassNames',{{'setosa','versicolor','virginica'}},'ClassProbs',1:3)
Data Types: single
 double
 char
 string
 struct
'ResponseName'
— Response variable name'Y'
(default)  character vector  string scalarResponse variable name, specified as the commaseparated pair consisting of
'ResponseName'
and a character vector or string scalar.
If you supply Y
, then you can
use 'ResponseName'
to specify a name for the response
variable.
If you supply ResponseVarName
or formula
,
then you cannot use 'ResponseName'
.
Example: 'ResponseName','response'
Data Types: char
 string
'ScoreTransform'
— Score transformation'none'
(default)  'doublelogit'
 'invlogit'
 'ismax'
 'logit'
 function handle  ...Score transformation, specified as the commaseparated pair consisting of
'ScoreTransform'
and a character vector, string scalar, or
function handle.
This table summarizes the available character vectors and string scalars.
Value  Description 

'doublelogit'  1/(1 + e^{–2x}) 
'invlogit'  log(x / (1 – x)) 
'ismax'  Sets the score for the class with the largest score to 1, and sets the scores for all other classes to 0 
'logit'  1/(1 + e^{–x}) 
'none' or 'identity'  x (no transformation) 
'sign'  –1 for x < 0 0 for x = 0 1 for x > 0 
'symmetric'  2x – 1 
'symmetricismax'  Sets the score for the class with the largest score to 1, and sets the scores for all other classes to –1 
'symmetriclogit'  2/(1 + e^{–x}) – 1 
For a MATLAB function or a function you define, use its function handle for the score transform. The function handle must accept a matrix (the original scores) and return a matrix of the same size (the transformed scores).
Example: 'ScoreTransform','logit'
Data Types: char
 string
 function_handle
'Weights'
— Observation weightsTbl
Observation weights, specified as the commaseparated pair consisting
of 'Weights'
and a numeric vector of positive values
or name of a variable in Tbl
. The software weighs
the observations in each row of X
or Tbl
with
the corresponding value in Weights
. The size of Weights
must
equal the number of rows of X
or Tbl
.
If you specify the input data as a table Tbl
, then
Weights
can be the name of a variable in Tbl
that contains a numeric vector. In this case, you must specify
Weights
as a character vector or string scalar. For example, if
the weights vector W
is stored as Tbl.W
, then
specify it as 'W'
. Otherwise, the software treats all columns of
Tbl
, including W
, as predictors or the
response when training the model.
The software normalizes Weights
to sum up
to the value of the prior probability in the respective class.
By default, Weights
is ones(
,
where n
,1)n
is the number of observations in X
or Tbl
.
Data Types: double
 single
 char
 string
'OptimizeHyperparameters'
— Parameters to optimize'none'
(default)  'auto'
 'all'
 string array or cell array of eligible parameter names  vector of optimizableVariable
objectsParameters to optimize, specified as the commaseparated pair
consisting of 'OptimizeHyperparameters'
and one of
the following:
'none'
— Do not optimize.
'auto'
— Use
{'Coding'}
along with the default
parameters for the specified
Learners
:
Learners
=
'svm'
(default) —
{'BoxConstraint','KernelScale'}
Learners
=
'discriminant'
—
{'Delta','Gamma'}
Learners
=
'kernel'
—
{'KernelScale','Lambda'}
Learners
=
'knn'
—
{'Distance','NumNeighbors'}
Learners
=
'linear'
—
{'Lambda','Learner'}
Learners
=
'naivebayes'
—
{'DistributionNames','Width'}
Learners
=
'tree'
—
{'MinLeafSize'}
'all'
— Optimize all eligible
parameters.
String array or cell array of eligible parameter names
Vector of optimizableVariable
objects,
typically the output of hyperparameters
The optimization attempts to minimize the crossvalidation loss
(error) for fitcecoc
by varying the parameters. For
information about crossvalidation loss in a different context, see
Classification Loss. To control the
crossvalidation type and other aspects of the optimization, use the
HyperparameterOptimizationOptions
namevalue
pair.
Note
'OptimizeHyperparameters'
values override any values you set using
other namevalue pair arguments. For example, setting
'OptimizeHyperparameters'
to 'auto'
causes the
'auto'
values to apply.
The eligible parameters for fitcecoc
are:
Coding
—
fitcecoc
searches among
'onevsall'
and
'onevsone'
.
The eligible hyperparameters for the chosen
Learners
, as specified in this
table.
Learners  Eligible
Hyperparameters (Bold = Default)  Default Range 

'discriminant'  Delta  Logscaled in the range
[1e6,1e3] 
DiscrimType  'linear' ,
'quadratic' ,
'diagLinear' ,
'diagQuadratic' ,
'pseudoLinear' , and
'pseudoQuadratic'  
Gamma  Real values in
[0,1]  
'kernel'  Lambda  Positive values logscaled in the range
[1e3/NumObservations,1e3/NumObservations] 
KernelScale  Positive values logscaled in the range
[1e3,1e3]  
Learner  'svm' and
'logistic'  
NumExpansionDimensions  Integers logscaled in the range
[100,10000]  
'knn'  Distance  'cityblock' ,
'chebychev' ,
'correlation' ,
'cosine' ,
'euclidean' ,
'hamming' ,
'jaccard' ,
'mahalanobis' ,
'minkowski' ,
'seuclidean' , and
'spearman' 
DistanceWeight  'equal' ,
'inverse' , and
'squaredinverse'  
Exponent  Positive values in
[0.5,3]  
NumNeighbors  Positive integer values logscaled in the
range [1,
max(2,round(NumObservations/2))]  
Standardize  'true' and
'false'  
'linear'  Lambda  Positive values logscaled in the range
[1e5/NumObservations,1e5/NumObservations] 
Learner  'svm' and
'logistic'  
Regularization  'ridge' and
'lasso'  
'naivebayes'  DistributionNames  'normal' and
'kernel' 
Width  Positive values logscaled in the range
[MinPredictorDiff/4,max(MaxPredictorRange,MinPredictorDiff)]  
Kernel  'normal' ,
'box' ,
'epanechnikov' , and
'triangle'  
'svm'  BoxConstraint  Positive values logscaled in the range
[1e3,1e3] 
KernelScale  Positive values logscaled in the range
[1e3,1e3]  
KernelFunction  'gaussian' ,
'linear' , and
'polynomial'  
PolynomialOrder  Integers in the range
[2,4]  
Standardize  'true' and
'false'  
'tree'  MaxNumSplits  Integers logscaled in the range
[1,max(2,NumObservations1)] 
MinLeafSize  Integers logscaled in the range
[1,max(2,floor(NumObservations/2))]  
NumVariablesToSample  Integers in the range
[1,max(2,NumPredictors)]  
SplitCriterion  'gdi' ,
'deviance' , and
'twoing' 
Alternatively, use hyperparameters
with your chosen Learners
, such as
load fisheriris % hyperparameters requires data and learner params = hyperparameters('fitcecoc',meas,species,'svm');
To see the eligible and default hyperparameters, examine
params
.
Set nondefault parameters by passing a vector of
optimizableVariable
objects that have nondefault
values. For example,
load fisheriris params = hyperparameters('fitcecoc',meas,species,'svm'); params(2).Range = [1e4,1e6];
Pass params
as the value of
OptimizeHyperparameters
.
By default, iterative display appears at the command line, and
plots appear according to the number of hyperparameters in the optimization. For the
optimization and plots, the objective function is log(1 + crossvalidation loss) for regression and the misclassification rate for classification. To control
the iterative display, set the Verbose
field of the
'HyperparameterOptimizationOptions'
namevalue pair argument. To
control the plots, set the ShowPlots
field of the
'HyperparameterOptimizationOptions'
namevalue pair argument.
For an example, see Optimize ECOC Classifier.
Example: 'auto'
'HyperparameterOptimizationOptions'
— Options for optimizationOptions for optimization, specified as the commaseparated pair consisting of
'HyperparameterOptimizationOptions'
and a structure. This
argument modifies the effect of the OptimizeHyperparameters
namevalue pair argument. All fields in the structure are optional.
Field Name  Values  Default 

Optimizer 
 'bayesopt' 
AcquisitionFunctionName 
Acquisition functions whose names include
 'expectedimprovementpersecondplus' 
MaxObjectiveEvaluations  Maximum number of objective function evaluations.  30 for 'bayesopt' or 'randomsearch' , and the entire grid for 'gridsearch' 
MaxTime  Time limit, specified as a positive real. The time limit is in seconds, as measured by  Inf 
NumGridDivisions  For 'gridsearch' , the number of values in each dimension. The value can be
a vector of positive integers giving the number of
values for each dimension, or a scalar that
applies to all dimensions. This field is ignored
for categorical variables.  10 
ShowPlots  Logical value indicating whether to show plots. If true , this field plots
the best objective function value against the
iteration number. If there are one or two
optimization parameters, and if
Optimizer is
'bayesopt' , then
ShowPlots also plots a model of
the objective function against the
parameters.  true 
SaveIntermediateResults  Logical value indicating whether to save results when Optimizer is
'bayesopt' . If
true , this field overwrites a
workspace variable named
'BayesoptResults' at each
iteration. The variable is a BayesianOptimization object.  false 
Verbose  Display to the command line.
For details, see the
 1 
UseParallel  Logical value indicating whether to run Bayesian optimization in parallel, which requires Parallel Computing Toolbox. Due to the nonreproducibility of parallel timing, parallel Bayesian optimization does not necessarily yield reproducible results. For details, see Parallel Bayesian Optimization.  false 
Repartition  Logical value indicating whether to repartition the crossvalidation at every iteration. If
 false 
Use no more than one of the following three field names.  
CVPartition  A cvpartition object, as created by cvpartition .  'Kfold',5 if you do not specify any crossvalidation
field 
Holdout  A scalar in the range (0,1) representing the holdout fraction.  
Kfold  An integer greater than 1. 
Example: 'HyperparameterOptimizationOptions',struct('MaxObjectiveEvaluations',60)
Data Types: struct
Mdl
— Trained ECOC modelClassificationECOC
model object  CompactClassificationECOC
model object  ClassificationPartitionedECOC
crossvalidated model
object  ClassificationPartitionedLinearECOC
crossvalidated
model object  ClassificationPartitionedKernelECOC
crossvalidated
model objectTrained ECOC classifier, returned as a ClassificationECOC
or
CompactClassificationECOC
model
object, or a ClassificationPartitionedECOC
, ClassificationPartitionedLinearECOC
, or
ClassificationPartitionedKernelECOC
crossvalidated
model object.
This table shows how the types of model objects returned by fitcecoc
depend on the type of binary learners you specify and whether you perform
crossvalidation.
Linear Classification Model Learners  Kernel Classification Model Learners  CrossValidation  Returned Model Object 

No  No  No  ClassificationECOC 
No  No  Yes  ClassificationPartitionedECOC 
Yes  No  No  CompactClassificationECOC 
Yes  No  Yes  ClassificationPartitionedLinearECOC 
No  Yes  No  CompactClassificationECOC 
No  Yes  Yes  ClassificationPartitionedKernelECOC 
HyperparameterOptimizationResults
— Description of crossvalidation optimization of hyperparametersBayesianOptimization
object  table of hyperparameters and associated valuesDescription of the crossvalidation optimization of hyperparameters,
returned as a BayesianOptimization
object or a
table of hyperparameters and associated values.
HyperparameterOptimizationResults
is nonempty when
the OptimizeHyperparameters
namevalue pair argument is
nonempty and the Learners
namevalue pair argument
designates linear or kernel binary learners. The value depends on the
setting of the HyperparameterOptimizationOptions
namevalue pair argument:
'bayesopt'
(default) — Object of class
BayesianOptimization
'gridsearch'
or
'randomsearch'
— Table of
hyperparameters used, observed objective function values
(crossvalidation loss), and rank of observation from smallest
(best) to highest (worst)
Data Types: table
fitcecoc
supports sparse matrices
for training linear classification models only. For all other models,
supply a full matrix of predictor data instead.
A binary loss is a function of the class and classification score that determines how well a binary learner classifies an observation into the class.
Suppose the following:
m_{kj} is element (k,j) of the coding design matrix M (that is, the code corresponding to class k of binary learner j).
s_{j} is the score of binary learner j for an observation.
g is the binary loss function.
$$\widehat{k}$$ is the predicted class for the observation.
In lossbased decoding [Escalera et al.], the class producing the minimum sum of the binary losses over binary learners determines the predicted class of an observation, that is,
$$\widehat{k}=\underset{k}{\text{argmin}}{\displaystyle \sum _{j=1}^{L}\left{m}_{kj}\rightg}({m}_{kj},{s}_{j}).$$
In lossweighted decoding [Escalera et al.], the class producing the minimum average of the binary losses over binary learners determines the predicted class of an observation, that is,
$$\widehat{k}=\underset{k}{\text{argmin}}\frac{{\displaystyle \sum _{j=1}^{L}\left{m}_{kj}\rightg}({m}_{kj},{s}_{j})}{{\displaystyle \sum}_{j=1}^{L}\left{m}_{kj}\right}.$$
Allwein et al. suggest that lossweighted decoding improves classification accuracy by keeping loss values for all classes in the same dynamic range.
This table summarizes the supported loss functions, where y_{j} is a class label for a particular binary learner (in the set {–1,1,0}), s_{j} is the score for observation j, and g(y_{j},s_{j}).
Value  Description  Score Domain  g(y_{j},s_{j}) 

'binodeviance'  Binomial deviance  (–∞,∞)  log[1 + exp(–2y_{j}s_{j})]/[2log(2)] 
'exponential'  Exponential  (–∞,∞)  exp(–y_{j}s_{j})/2 
'hamming'  Hamming  [0,1] or (–∞,∞)  [1 – sign(y_{j}s_{j})]/2 
'hinge'  Hinge  (–∞,∞)  max(0,1 – y_{j}s_{j})/2 
'linear'  Linear  (–∞,∞)  (1 – y_{j}s_{j})/2 
'logit'  Logistic  (–∞,∞)  log[1 + exp(–y_{j}s_{j})]/[2log(2)] 
'quadratic'  Quadratic  [0,1]  [1 – y_{j}(2s_{j} – 1)]^{2}/2 
The software normalizes binary losses such that the loss is 0.5 when y_{j} = 0, and aggregates using the average of the binary learners [Allwein et al.].
Do not confuse the binary loss with the overall classification loss (specified by the
'LossFun'
namevalue pair argument of the loss
and
predict
object functions), which measures how well an ECOC classifier
performs as a whole.
A coding design is a matrix where elements direct which classes are trained by each binary learner, that is, how the multiclass problem is reduced to a series of binary problems.
Each row of the coding design corresponds to a distinct class, and each column corresponds to a binary learner. In a ternary coding design, for a particular column (or binary learner):
A row containing 1 directs the binary learner to group all observations in the corresponding class into a positive class.
A row containing –1 directs the binary learner to group all observations in the corresponding class into a negative class.
A row containing 0 directs the binary learner to ignore all observations in the corresponding class.
Coding design matrices with large, minimal, pairwise row distances based on the Hamming measure are optimal. For details on the pairwise row distance, see Random Coding Design Matrices and [4].
This table describes popular coding designs.
Coding Design  Description  Number of Learners  Minimal Pairwise Row Distance 

oneversusall (OVA)  For each binary learner, one class is positive and the rest are negative. This design exhausts all combinations of positive class assignments.  K  2 
oneversusone (OVO)  For each binary learner, one class is positive, another is negative, and the rest are ignored. This design exhausts all combinations of class pair assignments.  K(K – 1)/2  1 
binary complete  This design partitions the classes into all binary
combinations, and does not ignore any classes. That is, all class
assignments are  2^{K – 1} – 1  2^{K – 2} 
ternary complete  This design partitions the classes into all ternary
combinations. That is, all class assignments are
 (3^{K} – 2^{K + 1} + 1)/2  3^{K – 2} 
ordinal  For the first binary learner, the first class is negative and the rest are positive. For the second binary learner, the first two classes are negative and the rest are positive, and so on.  K – 1  1 
dense random  For each binary learner, the software randomly assigns classes into positive or negative classes, with at least one of each type. For more details, see Random Coding Design Matrices.  Random, but approximately 10 log_{2}K  Variable 
sparse random  For each binary learner, the software randomly assigns classes as positive or negative with probability 0.25 for each, and ignores classes with probability 0.5. For more details, see Random Coding Design Matrices.  Random, but approximately 15 log_{2}K  Variable 
This plot compares the number of binary learners for the coding designs with increasing K.
An errorcorrecting output codes (ECOC) model reduces the problem of classification with three or more classes to a set of binary classification problems.
ECOC classification requires a coding design, which determines the classes that the binary learners train on, and a decoding scheme, which determines how the results (predictions) of the binary classifiers are aggregated.
Assume the following:
The classification problem has three classes.
The coding design is oneversusone. For three classes, this coding design is
$$\begin{array}{cccc}& \text{Learner1}& \text{Learner2}& \text{Learner3}\\ \text{Class1}& 1& 1& 0\\ \text{Class2}& 1& 0& 1\\ \text{Class3}& 0& 1& 1\end{array}$$
The decoding scheme uses loss g.
The learners are SVMs.
To build this classification model, the ECOC algorithm follows these steps.
Learner 1 trains on observations in Class 1 or Class 2, and treats Class 1 as the positive class and Class 2 as the negative class. The other learners are trained similarly.
Let M be the coding design matrix with elements m_{kl}, and s_{l} be the predicted classification score for the positive class of learner l. The algorithm assigns a new observation to the class ($$\widehat{k}$$) that minimizes the aggregation of the losses for the L binary learners.
$$\widehat{k}=\underset{k}{\text{argmin}}\frac{{\displaystyle \sum}_{l=1}^{L}\left{m}_{kl}\rightg\left({m}_{kl},{s}_{l}\right)}{{\displaystyle \sum}_{l=1}^{L}\left{m}_{kl}\right}.$$
ECOC models can improve classification accuracy, compared to other multiclass models [2].
The number of binary learners grows with the number
of classes. For a problem with many classes, the binarycomplete
and ternarycomplete
coding
designs are not efficient. However:
If K ≤ 4, then use ternarycomplete
coding
design rather than sparserandom
.
If K ≤ 5, then use binarycomplete
coding
design rather than denserandom
.
You can display the coding design matrix of a trained
ECOC classifier by entering Mdl.CodingMatrix
into
the Command Window.
You should form a coding matrix using intimate knowledge of the application, and
taking into account computational constraints. If you have sufficient computational
power and time, then try several coding matrices and choose the one with the best
performance (e.g., check the confusion matrices for each model using confusionchart
).
Leaveoneout crossvalidation (Leaveout
)
is inefficient for data sets with many observations. Instead, use kfold
crossvalidation (KFold
).
After training a model, you can generate C/C++ code that predicts labels for new data. Generating C/C++ code requires MATLAB Coder™. For details, see Introduction to Code Generation.
Custom coding matrices must have a certain form. The software validates custom coding matrices by ensuring:
Every element is 1, 0, or 1.
Every column contains as least one 1 and one 1.
For all distinct column vectors u and v, u ≠ v and u ≠ v.
All rows vectors are unique.
The matrix can separate any two classes. That is, you can travel from any row to any other row following these rules:
You can move vertically from 1 to 1 or 1 to 1.
You can move horizontally from a nonzero element to another nonzero element.
You can use a column of the matrix for a vertical move only once.
If it is not possible to move from row i to row j using these rules, then classes i and j cannot be separated by the design. For example, in the coding design
$$\left[\begin{array}{cc}1& 0\\ 1& 0\\ 0& 1\\ 0& 1\end{array}\right]$$
classes 1 and 2 cannot be separated from classes 3 and 4 (that is, you cannot move horizontally from the 1 in row 2 to column 2 since there is a 0 in that position). Therefore, the software rejects this coding design.
If you use parallel computing (see Options
),
then fitcecoc
trains binary learners in parallel.
Prior probabilities — The software normalizes
the specified class prior probabilities (Prior
)
for each binary learner. Let M be the coding design
matrix and I(A,c)
be an indicator matrix. The indicator matrix has the same dimensions
as A. If the corresponding element of A is c,
then the indicator matrix has elements equaling one, and zero otherwise.
Let M_{+1} and M_{1} be KbyL matrices
such that:
M_{+1} = M○I(M,1),
where ○ is elementwise multiplication (that is, Mplus
= M.*(M == 1)
). Also, let $${m}_{l}^{(+1)}$$ be
column vector l of M_{+1}.
M_{1} = M○I(M,1)
(that is, Mminus = M.*(M == 1)
). Also, let $${m}_{l}^{(1)}$$ be column vector l of M_{1}.
Let $${\pi}_{l}^{+1}={m}_{l}^{(+1)}\xb0\pi $$ and $${\pi}_{l}^{1}={m}_{l}^{(1)}\xb0\pi $$, where π is
the vector of specified, class prior probabilities (Prior
).
Then, the positive and negative, scalar class prior probabilities for binary learner l are
$${\widehat{\pi}}_{l}^{(j)}=\frac{{\Vert {\pi}_{l}^{(j)}\Vert}_{1}}{{\Vert {\pi}_{l}^{(+1)}\Vert}_{1}+{\Vert {\pi}_{l}^{(1)}\Vert}_{1}},$$
where j = {1,1} and $${\Vert a\Vert}_{1}$$ is the onenorm of a.
Cost — The software normalizes the KbyK cost
matrix C (Cost
) for each binary
learner. For binary learner l, the cost of classifying
a negativeclass observation into the positive class is
$${c}_{l}^{+}={\left({\pi}_{l}^{(1)}\right)}^{\top}C{\pi}_{l}^{(+1)}.$$
Similarly, the cost of classifying a positiveclass observation into the negative class is
$${c}_{l}^{+}={\left({\pi}_{l}^{(+1)}\right)}^{\top}C{\pi}_{l}^{(1)}.$$
The cost matrix for binary learner l is
$${C}_{l}=\left[\begin{array}{cc}0& {c}_{l}^{+}\\ {c}_{l}^{+}& 0\end{array}\right].$$
ECOC models accommodate misclassification costs by incorporating
them with class prior probabilities. If you specify Prior
and Cost
,
then the software adjusts the class prior probabilities as follows:
$$\begin{array}{l}{\overline{\pi}}_{l}^{1}=\frac{{c}_{l}^{+}{\widehat{\pi}}_{l}^{1}}{{c}_{l}^{+}{\widehat{\pi}}_{l}^{1}+{c}^{+}{\widehat{\pi}}_{l}^{+1}}\\ {\overline{\pi}}_{l}^{+1}=\frac{{c}_{l}^{+}{\widehat{\pi}}_{l}^{+1}}{{c}_{l}^{+}{\widehat{\pi}}_{l}^{1}+{c}^{+}{\widehat{\pi}}_{l}^{+1}}.\end{array}$$
For a given number of classes K, the software generates random coding design matrices as follows.
The software generates one of these matrices:
Dense random — The software assigns 1 or –1 with equal probability to each element of the KbyL_{d} coding design matrix, where $${L}_{d}\approx \lceil 10{\mathrm{log}}_{2}K\rceil $$.
Sparse random — The software assigns 1 to each element of the KbyL_{s} coding design matrix with probability 0.25, –1 with probability 0.25, and 0 with probability 0.5, where $${L}_{s}\approx \lceil 15{\mathrm{log}}_{2}K\rceil $$.
If a column does not contain at least one 1 and at least one –1, then the software removes that column.
For distinct columns u and v, if u = v or u = –v, then the software removes v from the coding design matrix.
The software randomly generates 10,000 matrices by default, and retains the matrix with the largest, minimal, pairwise row distance based on the Hamming measure ([4]) given by
$$\Delta ({k}_{1},{k}_{2})=0.5{\displaystyle \sum}_{l=1}^{L}\left{m}_{{k}_{1}l}\right\left{m}_{{k}_{2}l}\right\left{m}_{{k}_{1}l}{m}_{{k}_{2}l}\right,$$
where m_{kjl} is an element of coding design matrix j.
By default and for efficiency, fitcecoc
empties the Alpha
, SupportVectorLabels
,
and SupportVectors
properties
for all linear SVM binary learners. fitcecoc
lists Beta
, rather than
Alpha
, in the model display.
To store Alpha
, SupportVectorLabels
, and
SupportVectors
, pass a linear SVM template that specifies storing
support vectors to fitcecoc
. For example,
enter:
t = templateSVM('SaveSupportVectors',true) Mdl = fitcecoc(X,Y,'Learners',t);
You can remove the support vectors and related values by passing the resulting
ClassificationECOC
model to
discardSupportVectors
.
[1] Allwein, E., R. Schapire, and Y. Singer. “Reducing multiclass to binary: A unifying approach for margin classiﬁers.” Journal of Machine Learning Research. Vol. 1, 2000, pp. 113–141.
[2] Fürnkranz, Johannes, “Round Robin Classification.” J. Mach. Learn. Res., Vol. 2, 2002, pp. 721–747.
[3] Escalera, S., O. Pujol, and P. Radeva. “On the decoding process in ternary errorcorrecting output codes.” IEEE Transactions on Pattern Analysis and Machine Intelligence. Vol. 32, Issue 7, 2010, pp. 120–134.
[4] Escalera, S., O. Pujol, and P. Radeva. “Separability of ternary codes for sparse designs of errorcorrecting output codes.” Pattern Recog. Lett., Vol. 30, Issue 3, 2009, pp. 285–297.
Usage notes and limitations:
Supported syntaxes are:
Mdl = fitcecoc(X,Y)
Mdl = fitcecoc(X,Y,Name,Value)
[Mdl,FitInfo,HyperparameterOptimizationResults] =
fitcecoc(X,Y,Name,Value)
— fitcecoc
returns the
additional output arguments FitInfo
and HyperparameterOptimizationResults
when you specify the
'OptimizeHyperparameters'
namevalue pair
argument.
The FitInfo
output argument is an empty structure array currently
reserved for possible future use.
Options related to crossvalidation are not supported. The supported namevalue pair arguments are:
'ClassNames'
'Cost'
'Coding'
— Default value is
'onevsall'
.
'HyperparameterOptimizationOptions'
— For
crossvalidation, tall optimization supports only 'Holdout'
validation. For example, you can specify
fitcecoc(X,Y,'OptimizeHyperparameters','auto','HyperparameterOptimizationOptions',struct('Holdout',0.2))
.
'Learners'
— Default value is 'linear'
.
You can specify 'linear'
,'kernel'
, a
templateLinear
or templateKernel
object,
or a cell array of such objects.
'OptimizeHyperparameters'
— When you use linear
binary learners, the value of the 'Regularization'
hyperparameter must be 'ridge'
.
'Prior'
'Verbose'
— Default value is 1
.
'Weights'
This additional namevalue pair argument is specific to tall arrays:
'NumConcurrent'
— A positive integer scalar specifying the
number of binary learners that are trained concurrently by combining file I/O
operations. The default value for 'NumConcurrent'
is
1
, which means fitcecoc
trains the
binary learners sequentially. 'NumConcurrent'
is most
beneficial when the input arrays cannot fit into the distributed cluster memory.
Otherwise, the input arrays can be cached and speedup is negligible.
If you run your code on Apache Spark™, NumConcurrent
is upper bounded by the memory
available for communications. Check the
'spark.executor.memory'
and
'spark.driver.memory'
properties in your Apache Spark configuration. See parallel.cluster.Hadoop
(Parallel Computing Toolbox) for more details. For more information
on Apache Spark and other execution environments that control where your code
runs, see Extend Tall Arrays with Other Products.
For more information, see Tall Arrays.
To run in parallel, set the 'UseParallel'
option to
true
in one of these ways:
Set the 'UseParallel'
field of the options
structure to true
using statset
and specify the 'Options'
namevalue pair argument in
the call to fitceoc
.
For example:
'Options',statset('UseParallel',true)
For more information, see the 'Options'
namevalue
pair argument.
Perform parallel hyperparameter optimization by using the
'HyperparameterOptions',struct('UseParallel',true)
namevalue pair argument in the call to
fitceoc
.
For more information on parallel hyperparameter optimization, see Parallel Bayesian Optimization.
ClassificationECOC
 ClassificationPartitionedECOC
 ClassificationPartitionedKernelECOC
 ClassificationPartitionedLinearECOC
 CompactClassificationECOC
 designecoc
 loss
 predict
 statset
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