open .mat files and concatenate their matrix contents

James on 29 Jun 2012

Link

Thanks Walter. The link was useful and I started but got stuck - the program hangs with no output:

if true
    % code

      %3 Files: Mat0.mat, Mat1.mat,Mat2.mat (each mat file contains a   matrix   with corresponding number(e.g., mut0) with a dimension, 2million by 50)
    %Allocate storage for matrix data inside mat files
     matData = [];

   %Loop through mat files and store concatenated matrices into matData[]
    for k = 0:2
    matFilename = sprintf('Mat%d.mat',k);
    matLoad = load(matFilename);
    %matData = 'matLoad.mut%d';
    matData = [matData; matLoad.mut%d];
    end;
    end

Please help!

James

Walter Roberson on 29 Jun 2012

Link

matData = [matData; matLoad.(num2str(k, 'mut%d'))];

James Tursa on 29 Jun 2012

Link

IMO that is not a good way to do this in general. At every iteration in the loop you need to copy all of the data to a new memory block to do the concatenation. This drags performance. What I would do is read each iteration into an element of a cell array. Then after all of the files have been read concatenate all of the cell array contents into the big matrix. That way the data only gets copies once, not many times during the file reading iterations.

James on 30 Jun 2012

Link

Thanks Walter. It worked! I appreciate James' comment about efficiency, and I tried to implement the codes as follows:

 matData = [];
 for k = 0:2
 matFilename = sprintf('mut%d.mat',k);
 matLoad = load(matFilename);
 similar = cell(size(matLoad.(num2str(k, 'mut%d'))));
 end;
 matData = [matData; similar];

But, I'm not sure if this what you meant.

James

0 Comments

Tags

Products

1 Answer

4 Comments