Error: subscripted assignment dimension mismatch for loop

Hello,

The error I get is : subscripted assignment dimension mismatch at line 40. [line 40 = dataSet(:,1) = str2double(dataArray{1});]

I am trying to loop across a specific number of files in a directory, Everything goes smooth for the first few runs and at random counter values (chopIndex) I get the error. When I did check my workspace, for the iterations where there is no error the size of "dataSet" is 101000x3 double, but post error the size of "dataSet" is 102000x3double.

When I restart and run the code the same issue occurs at a different iteration.

Why does this happen? I'm confused. Please Help.

I have attached my code.

Thank You. SP

Answer 1

[Geoff Hayes]

SP - the error message is telling you that you are making an invalid assignment. For example, the following produces the same error

 dataSet = zeros(5,1);
 dataSet(:,1) = [1:4]';

because we are trying to assign a column of four elements to a column that is expecting five elements.

I suspect that what might be happening is that many of your files which populate dataArray have the same number of rows, so subsequent iterations of your

 for i = 1:numOfFiles

allow us to do these assignments

 dataSet(:,1) = str2double(dataArray{1});
 dataSet(:,2) = str2double(dataArray{2});
 dataSet(:,3) = str2double(dataArray{3});

without error because each dataArray has the same number of rows as the dataArray from the previous iteration. This works fine until we encounter an iteration where dataArray has a different number of rows and the error arises.

What you can do, since you don't care to keep the data from one iteration to the next, is just reset dataSet before the assignment. Something like

 dataSet = zeros(size(dataArray,1),3);
 dataSet(:,1) = str2double(dataArray{1});
 dataSet(:,2) = str2double(dataArray{2});
 dataSet(:,3) = str2double(dataArray{3});

In the above, we size dataSet to be a matrix with the same number of rows as dataArray with three columns. Try this and see what happens!

[SP]

Geoff Haynes. Thank you for the answer. I understood what happened and checked my dataArray file (its an lvm file) when I checked the original data file the size was varying from file to file.

However when I sized dataSet to zeros of dataArray size [dataSet = zeros(size(dataArray,1),3);], I got the same error. So I assigned dataSet and empty martix instead [ dataSet = [] ]. This worked and I could compile through my list of files well. BUT now I have another issue.

New issue:

fMat is a matrix filled by chopping a portion of dataArray column 2

    rowNum=1; %n=1;
    colLength=size(dataSet,1); 
    for chopIndex = 1:size(dataSet,1)-1 
        if sign(dataSet(chopIndex+1, 3)) ~= sign(dataSet(chopIndex, 3)) 
             if chopIndex > 250 && chopIndex < colLength-1000 
                 fMat(:,rowNum)=dataSet(chopIndex-250:chopIndex+750,2); 
                 rowNum=rowNum+1; %n=n+1;
             end % end
        end %end
    end %end

this is done if the 2 if conditions are satisfied.

Now, When I check the output xls file; for a random file in the list of files - there is an extra column in the fMat, as a result of the extra column, the mMat value is different.

By different I mean: I have an original code (attached) that doesnt loop though files but the user has to select each file and run it the code #numberOfFiles times. When I run the file with the original code. the mMat value is different.

Why is the fMat different ? Is it because of the loop?

Please help. Thank You. SP

I hope I could convey my issue without confusion.

[Geoff Hayes]

As I don't have access to your data, it will be easier for you to step through the code using the debugger. Try it and see if you can determine why fMat is different.

[SP]

Geoff Hayes, Thank you again for the reply.

I think I figured the issue out, I wasnt clearing the variable fMat, so it was holding information of the previous file (that had a different size, hence a larger fMat, as discussed earlier) Hence the extra column. I used "clearvars" and cleared fMat, mMat, sMat and dataset. So for every file - its a fresh set of variables. It works now. Hope its the right way to do it.

Thank you for the help! SP