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load several (one after another ) .mat Files via a For-Loop Job

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Hello, i have a Program that is in the Folder-Directory: Main. And i have some several numbered .mat-Files with the Variable Buff that are in the Folder Directory Main/Combination:
combinations_1.mat
combinations_2.mat
combinations_3.mat
...and so on
My Program should load the first combinations_1.mat and to something:
for I = 1:size(Buff,1)
% calculate some stuff
end
After the Loop is done it should load combinations_2 and start the Loop again
My Idea is:
d = dir('*.mat'); % only looking for .mat-Files
Number_mat = length(d); % number of .mat-Files
for i=1:Number
load(['combinations_' num2str(i) '.mat'])
end
But i no idea how i can this combine with the For-Loop. Hope everybody understand my aim, big thanks

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Accepted Answer

Sarah Wait Zaranek
Sarah Wait Zaranek on 17 Jan 2013
Edited: Jan on 17 Jan 2013
Unless I am missing something, I think the easiest thing would be to do a nested for loop.
for ii = 1: Number
load(['combinations_' num2str(ii) '.mat'])
for jj = 1:size(Buff,1)
% calculate some stuff
end
end

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Veena Chatti
Veena Chatti on 3 Jan 2020
Hi Sarah,
I also have a similar question. I am trying to subplot the same variable from each of N mat files in a folder. I tried a nested for loop and an if condition. Right now it puts the same variable in all rows (the first one it loads). But I think it might work if I could load each mat file sequentially and refer to the same subplot in the loop. Please could you think of some ways I could adapt my code to do this? I would greatly appreciate your tips! My current code is as follows:
%%
read_folder = '...';
write_folder = '...';
cd(read_folder);
files = dir('*.mat');
N=numel(files);
R_y = [array of numbers]';
A_y = [another array of numbers]';
figure;
fig = gcf;
for i = 1:N
for j = 1:6 %will need to change this as per numel(files).
load(files(i).name, 'R', 'A')
[pathstr,name,ext] = fileparts(files(i).name);
newFilename = fullfile(pathstr,name);
subplot(N,2,j)
if mod(j,2) == 0
subplot(N,2,j);
plot(A_y, A);
else mod(j,2) == 1 ;
subplot(N,2,j);
plot(R_y, R);
end
end
cd(write_folder);
saveas(fig, Image_name, 'png');
cd(read_folder);
end
Thanks!
Image Analyst
Image Analyst on 3 Jan 2020
I'd do
rows = ceil(sqrt(N*6));
outside the loop, then inside the loop do
subplot(rows, rows, (i-1)*6+j);
This will make a square matrix of plots and each plot will go into a separate, new plot in that matrix.
Veena Chatti
Veena Chatti on 12 Jan 2020
Thanks for your suggestion. I will test it soon.
Someone from MATLAB, Pujitha Narra, posted an answer on the question I asked, their solution worked really well!

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More Answers (1)

Image Analyst
Image Analyst on 17 Jan 2013
You can use dir() to get a list of the filenames. Then you should check that the variable is actually in the mat file. Try this. It's a fairly robust adaptation of code already in the FAQ.
myFolder = 'Main/combinations'; % May need to correct this.
if ~isdir(myFolder)
errorMessage = sprintf('Error: The following folder does not exist:\n%s', myFolder);
uiwait(warndlg(errorMessage));
return;
end
filePattern = fullfile(myFolder, 'combinations*.mat');
matFiles = dir(filePattern);
for k = 1:length(matFiles)
matFilename = fullfile(myFolder, matFiles(k).name)
matData = load(matFilename); % Retrieves a structure.
% See if Buff actually exists in the data structure.
hasField = isfield(matData, 'Buff');
if ~hasField
% Alert user in popup window.
warningMessage = sprintf('Buff is not in %s\n', matFilename);
uiwait(warndlg(warningMessage));
% It's not there, so skip the rest of the loop.
continue; % Go to the next iteration.
end
% If you get to here, Buff existed in the file.
Buff = matData.Buff; % Extract the Buff from the structure.
for row = 1 : size(Buff,1)
% Calculate some stuff
end
end

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