How one can assign the indices of train and test data manually?

The function "cvpartition" randomly chooses a subset of data for train and the rest for test in K-Fold cross validation. However, it is not possible to change the index of each data partition in a defined cvpartition object. I was wondering if someone here knows a way to do it. For example if we had a dataset with 300 samples (observations), the following code makes 10 random distinct partitions for train and test data.

CVO = cvpartition(300,'k',10)

Now if I want to assign first 270 samples as train and the rest as test for the first partition I would do this:

CVO.training(1) = logical([ones(270,1);zeros(30,1)])

Which does not work and returns an error:

Assignment not supported because the result of method 'training' is a temporary value.

Any suggestion is greatly appreciated!

[GIULIA CISOTTO]

Did you find solution to this problem? If yes, could you kindly share it.. It would be very useful! Thanks