Different behavior of 'activations' function of Neural Network Toolbox between 2017b and 2018a.

If I tried CNN sample code obtained here, I got error on 2018a and not on 2017a. Is it a bug or expected behavior? How can I fixed it on 2018a?

1. Obtained sample code here.https://jp.mathworks.com/matlabcentral/fileexchange/57280-cnn---transfer-learning-example
2. Run classifyFlowers.m
3. Hit following error

Error: classifyFlowers (line 39)
classifier = fitcsvm(trainingFeatures, trainingSet.Labels);

Findings:

I found that the size of matrix of returned value from 'activations' function was different.

trainingFeatures = activations(convnet, trainingSet, featureLayer, 'MiniBatchSize', 1);

2017b (Expected):

>> size(trainingFeatures)
ans =

           112        4096

2018a (Not Expected):

>> size(trainingFeatures)
ans =
           1           1        4096         112

Answer 1

[Johannes Bergstrom]

This is the expected behavior. Please see the release notes under 'Functionality Being Removed or Changed', https://www.mathworks.com/help/nnet/release-notes.html

Default output format of activations: In R2018a, the new default output format of activations is a 4-D array. To reproduce the old default behavior, set the 'OutputAs' value to 'rows'.

[HIDEYA MATSUDA]

Thank you. I could solve the problem.