help with error in my code

Hi can someone help me understand the mistake in my code, i followed the correct syntax from https://uk.mathworks.com/help/bioinfo/ref/classperf.html

i keep getting the error

operator "==" not supported for operands of type "cvpartition"

error in line 24

test = (indices == 1)

k = 4;
n = 699; %sample lenght
rng ('default')
indices = cvpartition(n,'kfold', k);
for i = 1:k
  test= (indices == i); train = ~test;
  class = classify(InputVariable(test,:),InputVariable(train,:),OutputVariable(train,:));
  classperf(cp,class,test);
end
cp.ErrorRate  
 
plotconfusion(testTarget, testY)

[Walter Roberson]

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Many of the people who volunteer here do so on the understanding that the answers are available to everyone. I did not research and spend the time writing up my response to help you personally, I did so in order that anyone else who also had a similar question would also be able to see the answer.

[Rik]

Original post from Google cache.

[Stephen23]

Original question by Dilpreet kaur retrieved from Google Cache:

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http://web.archive.org/web/20210102054019/https://www.mathworks.com/matlabcentral/answers/706018-help-with-error-in-my-code

help with error in my code

Hi can someone help me understand the mistake in my code, i followed the correct syntax from https://uk.mathworks.com/help/bioinfo/ref/classperf.html

i keep getting the error

operator "==" not supported for operands of type "cvpartition"

error in line 24

test = (indices == 1)

k = 4;
n = 699; %sample lenght
rng ('default')
indices = cvpartition(n,'kfold', k);
for i = 1:k
  test= (indices == i); train = ~test;
  class = classify(InputVariable(test,:),InputVariable(train,:),OutputVariable(train,:));
  classperf(cp,class,test);
end
cp.ErrorRate  
 
plotconfusion(testTarget, testY)

[Rena Berman]

(Answers Dev) Restored edit

Answer 1

[Image Analyst]

I get this:

k = 4;
n = 699; %sample lenght
rng ('default')
indices = cvpartition(n,'kfold', k)

indices =

K-fold cross validation partition

NumObservations: 699

NumTestSets: 4

TrainSize: 525 524 524 524

TestSize: 174 175 175 175

You're not using indices correctly. It's an object, not a list of indices. If you want a listof indices, use randperm().

Answer 2

[Walter Roberson]

cvpartition does not return indices.

rng ('default')
nfold = 4;
cvfolds = cvpartition(699,'kfold', nfold);

cp = classperf(OutputVariable); % initializes the CP object

for i = 1:nfold
  test = cvfolds.test(i);
  train = cvfolds.training(i);
  class = classify(InputVariable(test,:), InputVariable(train,:), OutputVariable(train,:));
  classperf(cp, class, test);
end
cp.ErrorRate