This is a MATLAB question: the problem is caused by interactions with MATLAB files and Python/numpy. I am tying to write a 3-D array of type uint8 in MATLAB, and then read it in Python using numpy. This is the MATLAB code that creates the file:
voxels = zeros(30, 30, 30);
....
fileID1 = fopen(fullFileNameOut,'w','s');
fwrite(fileID1, voxels, 'uint8');
fclose(fileID1);
This is the Python code that tries to read the file:
filename = 'File3DArray.mat'
arr = scipy.io.loadmat(filename)['instance'].astype(np.uint8)
This is the error that I get when I run the python code:(I think this is the source of the problem. What is MM
raise TypeError('Expecting miMATRIX type here, got %d' % mdtype)
This is the output of the Linux command 'file' on the 3D array file that I created (I think this is the source of the problem. What is MMDF Mailbox?):
File3DArray.mat: MMDF mailbox
This is the output of the same Linux command 'file' on another 3D array file that was created by someone else in MATLAB:
GoodFile.mat: Matlab v5 mat-file (little endian) version 0x0100
I want the files I create in MATLAB to be the same as GoodFile.mat (so that I can read them with the Python/Numpy code segment above). The output of the Linux 'file' command should be the same as the GoodFile output, I think. What is the MATLAB code that does that?
To create a MAT-file, use the MATLAB save command:
voxels = zeros(30, 30, 30, 'uint8');
save(fullFileNameOut, 'voxels', '-v7')
You need to add '-v7' (or '-v6') as an argument to save to create a file in an older format, as SciPy doesn't recognize the '-v7.3' files created by default.