compare index 1 to index s within loop. index exceed matrix dim

I have 12 files (M) each with 12 columns to which I want to compare each file columns to another file columns.

for s =1:numel(M)

     if all(strcmpi(M(1),M(s))) == 1

        M = M(s);
     end
  end

However, I am getting index exceed matrix dimension. Any help as to how to improve this loop would be nice.

[Azzi Abdelmalek]

12 files or 12 matrices?

[Leyon]

12 matrices each with 12 columns. The result of strcmpi would be a row with 12 values to which "all" will check if there 1s.

[Walter Roberson]

Perhaps you want any() instead of all() ?

[Leyon]

I need an all because any() says that the two matrices can have specific columns that are equal. I need all the columns to be equal across all the matrices

Answer 1

[Walter Roberson]

The first time the test succeeds, you are going to replace your array M with the single element M(s) . That leaves M as only a single element long, so the next iteration of the loop attempting to index it by anything other than 1 is going to fail.

[Leyon]

The loop iterates correctly but doesn't stop correctly. Index 12 compares against 11, but it then tries to compares 13 against 12 which there is no 13 and thus "index exceeds matrix" error. How can i gt it to loop correctly or compare the matrices correctly?

[Walter Roberson]

Your only defined desired stopping condition is reaching the end of M. If that is the desired stopping condition then you cannot replace M with M(s)

[Leyon]

As before, how would I be able to compare the columns in the matrices?

[Walter Roberson]

You are doing an approximation of comparing columns. But when you find a match, you are overwriting the M array and then attempting to continue matching. Perhaps you want something more like,

M_target = M(false);   %copies the type but an empty matrix

for s =1:numel(M)

     if all(strcmpi(M(1),M(s))) == 1

        M_target = M(s);
     end
  end