Extract rows separately from multiple files.

I have 90 files each with three columns and about 2000 rows of data. I want to match/extract the first row in each of the files together, then the second, then the third and so on. Anyone know an efficient way of doing this? Thanks

[Jan]

It would be useful if you mention, in which format the files are written. It matters if they are MAT files, JPEG or text files.

Answer 1

[Jan]

The most efficient way is to read all files into an array and sort the data as you want.

To get a more explicit answer, please explain what "match/extract the first row in each of the files together" means. Without knowing this detail, an answer must remain very vague.

[C Smyth]

Thank you for your reply! When I say match/extract, I want to input the first row of each file into an equation, then repeat the equation with the second row of each file and so on. But instead of re-writing the equation is there a way to automatically do this. All of the files are MAT files. I hope this makes more sense. Thank you

[Jan]

Load all files in a loop:

Folder  = 'C:\Temp';  % Adjust this
DirList = dir(fullfile(Folder, '*.mat'));
nData   = numel(DirList);
Data    = cell(1, nData);
for k = 1:nData
  FileData = load(fullfile(Folder, DirList(k).name)); 
  Data{k}  = FileData;  % Or FileData.YourField, adjust this
end

Now you can process the data in a loop:

for kRow = 1:nRows
  Row = zeros(nData, ???);
  for kData = 1:nData
     Row(kData, :) = Data{kData}(kRow, :);
  end
  ... Do what you want with the Row data...
end

This is based on some guessing and assuming, because you did provide very few details only. But maybe the general idea gets clear.