How to process multiple dot mat file using for loop

Hello every one, please help me in solving this issue

I have thousands of mat files as shown in figure for sample. Each mat file contains a variable called ‘val’ which is 2 by 19000 matrices. What I need is to extract the first raw of ‘val’ of each dot mat file and save it by naming sequentially like “x1, x2, x3……..” Using for loop.

I have done for a single file successfully by the following algorithm

>> clear all

>> load('dist (1).mat')

>> x = val(1,:);

>> save('x1.mat', 'x')

I have attached some of the dot mat files

Thanks so much in advance for your help

Answer 1

[David Fletcher]

Wouldn't it be better to extract what you want into a single matrix and then just save the one matrix with all the data rather than having thousands of separate files? Having said that, a basic framework for doing what you want is:

clear

numberOfFiles= %enter number of files;

for iter=1:numberOfFiles
    fName=sprintf('dist (%d).mat',iter);
    x=load(fName);
    x=x.val(1,:);
    fName=sprintf('x%d.mat',iter);
    save(fName, 'x');
end

[Yared Daniel]

Thank you so much Mr. Fletcher this worked perfectly and you saved my time. As additional how could I extract what I want into a single matrix and then save the one matrix with all the data as you said?

[David Fletcher]

Assuming all the matrices are have the same number of columns, you can put everything into one matrix with each row being a separate data file

clear

numberOfFiles= %enter number of files;

for iter=1:numberOfFiles
    fName=sprintf('dist (%d).mat',iter);
    x=load(fName);
    allData(iter,:)=x.val(1,:)
end

save('data.mat', 'allData.mat')

If the size of the matrices are not the same you would have to use a cell array rather than a matrix

[Yared Daniel]

I got this error I think it is due the size of the matrices. how would use cell array sir?

Unable to perform assignment because the size of the left side is 1-by-19200 and

the size of the right side is 1-by-21600.

Error in AL_in (line 4)

allData(iter,:)=x.val(1,:)

[David Fletcher]

clear

numberOfFiles= %enter number of files;
for iter=1:numberOfFiles
    fName=sprintf('dist (%d).mat',iter);
    x=load(fName);
    allData{iter}=x.val(1,:)
end

save('data.mat', 'allData.mat')

[Yared Daniel]

I sincerely appreciate your help thank you so much