how to create and store a matrix from a dataset comprising of certain rows from the dataset.

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Apurva Jariwala
Apurva Jariwala 2019-2-27
评论： Apurva Jariwala 2019-2-27
Need to create a matrix from a dataset that selects certain rows depending on whether a given condition is fulfilled. For eg, from the IRIS dataset, create a matrix comprising of first 30 samples for each class.

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KSSV
KSSV 2019-2-27
load iris.dat
setosa = iris((iris(:,5)==1),:); % data for setosa
versicolor = iris((iris(:,5)==2),:); % data for versicolor
virginica = iris((iris(:,5)==3),:); % data for virginica
obsv_n = size(iris, 1); % total number of observations
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Apurva Jariwala
Apurva Jariwala 2019-2-27
Thanks for the response, i have written the following code to divide the iris dataset into training and testing dataset. Any help to reduce the lines of code is appreciated
setosa = Tnew((Tnew(:,5)==1),:); %Tnew is the iris dataset
Ttest1 = setosa(1:40,:);
Ttrain1 = setosa(41:50,:);
versicolor = Tnew((Tnew(:,5)==2),:);
Ttest2 = versicolor(1:40,:);
Ttrain2 = versicolor(41:50,:);
virginica = Tnew((Tnew(:,5)==3),:);
Ttest3 = virginica(1:40,:);
Ttrain3 = virginica(41:50,:);
Ttest = [Ttest1; Ttest2; Ttest3];
Ttrain = [Ttrain1; Ttrain2; Ttrain3];

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