How to specify the chunksize of large array saved in -v7.3 matfile?

Question

I'm saving large data array to mat file.

m = matfile('data.mat','writable',true);
m.X(1000,1000,10,50000) = nan(1,'single');
for ii = 1 : 50000
  % do some computation
  m.X(1:1000,1:1000,1:10,ii) = Y;
end

How can I set ChunkSize of X to [1000,1000,1,1]?

Don't think you can influence it. What is your goal behind changing the chunksize? — Daniel, Feb 05 '20 at 20:46
@Daniel because the matfile will be huge and in the postprocessing, I need to read them frame by frame. — wsdzbm, Feb 08 '20 at 02:03

score 0 · Accepted Answer · answered Feb 08 '20 at 07:09

You can't use the matfile command, but you use the HDF5 api. Since matfiles v7.3 use the HDF5 format, i guess it should also work on the reading side for you? Here is a small example from the documentation:

h5create('myfile.h5','/DS3',[20 Inf],'ChunkSize',[5 5]);
for j = 1:10
      data = j*ones(20,1);
      start = [1 j];
      count = [20 1];
      h5write('myfile.h5','/DS3',data,start,count);
end
h5disp('myfile.h5');

Source of the example

How to specify the chunksize of large array saved in -v7.3 matfile?

1 Answers1