Extracting data from confusion matrix fig

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M Umair 2022-5-22

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回答： Bala Tripura Bodapati 2022-5-26

Hi, How can i extract the data from a confusion matrix fig file?

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Bala Tripura Bodapati 2022-5-26

Hi Umair,

Could you specify whether the figure contains confusion matrix or confusion chart? Also could you specify what type of data do you want to extract specifically? Attaching an example would help me answer your query with more specificity.

M Umair 2022-5-26

SqueezeNet-CM.fig

Hello Bala,

Thanks for your time.

The figure contains confusion matrix (file attached). I want to extract all numerical values presented in the figure excluding the percentages.

Thank you

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Answer 1

Chunru 2022-5-26

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编辑：Chunru 2022-5-26

在 MATLAB Online 中打开

SqueezeNet-CM.fig

f = openfig('SqueezeNet-CM', 'visible');

h = findobj(f.Children(2).Children, 'Type', 'Text');

data = zeros(length(h), 1);

for i=1:length(h)

data(i) = sscanf(h(i).String, '%f');

end

m = 5;

data = reshape(data, [2*m m]);

data_number = data(4:2:end, 2:end)

data_number = 4×4

115 0 0 2 769 447 174 90 107 753 1020 681 209 0 6 427

data_number = data_number(end:-1:1, end:-1:1)

data_number = 4×4

427 6 0 209 681 1020 753 107 90 174 447 769 2 0 0 115

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Answer 2

Bala Tripura Bodapati 2022-5-26

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在 MATLAB Online 中打开

Hi Umair,

It is my understanding that you would like to extract the numeric values from confusion matrix plotted on a figure.

From the confusion matrix plotted using 'plotconfusion' function, there is no method to extract the numeric values.

Alternatively, you can plot the confusion matrix using the 'confusionchart' function on a figure and then extract the numeric values.

The following code illustrates the same:

load fisheriris
X = meas;
Y = species;
Mdl = fitcknn(X,Y,'NumNeighbors',5,'Standardize',1);
predictedY = resubPredict(Mdl);
fig=figure;
confusionchart(Y,predictedY);

'cm' is a confusion chart object. The 'NormalizedValues' property of this object outputs the numeric matrix:

matrix=cm.NormalizedValues

Refer the Matrices documentation for more information on accessing elements from a matrix.

Also, refer the confusionchart documentation for more information on confusion chart and graphics hierarchy documentation for more information on accessing figure object and it's children.