How to conditionally delete columns in a cell array

Hi,

I have a simple cell array that look like this:

input = {'A','B','A','A','A','A','A','A'; 'A','A','B','A','A','A','A','A'; 'A','A','A','A','A','A','A','A'}

What I want to do is to simply delete all the columns that dont contains 'B' but only those to the right hand side of the last column that contains a 'B'.

In other words the ouput would look like this:

ouput = {'A','B','A'; 'A','A','B'; 'A','A','A'}

How would I do that ?

Thank you,

Answer 1

[Star Strider]

Try this:

inputc = {'A','B','A','A','A','A','A','A'; 'A','A','B','A','A','A','A','A'; 'A','A','A','A','A','A','A','A'};
isB = cell2mat(cellfun(@(x)ismember('B',x), inputc, 'Uni',0));
[r,c] = find(isB, 1, 'last');
outputc = inputc(:,1:c)

producing:

outputc =

  3×3 cell array

    {'A'}    {'B'}    {'A'}
    {'A'}    {'A'}    {'B'}
    {'A'}    {'A'}    {'A'}

I could have combined ‘isB’ and the find call in one line, however breaking it into two lines is easier to understand.

.

[Blue]

Neat. Thank you.

[Star Strider]

As always, my pleasure!

Answer 2

[Guillaume]

If your cell array is indeed a cell array of single characters, then you'd be better off storing it as a char matrix:

input = cell2mat(input);

In which case:

[~, lastc] = max(input == 'B', [], 2);
output = input(:, 1:max(lastc))