Replacing values in a cell which is part of matrix

I have a cell column, which is a third column of a matrix named 'a'. The cell column contains values A,B,C,D and E. I just want to change all E's to D. Unfortunately this does not work with cells: a(a=='E')='D'; (I am aware that if I cell2mat the column the above will work, but I have to keep it in a cell format.) I suppose it can be done somehow with cellfun ...but how??? Regards

Answer 1

[Guillaume]

I have to keep it in a cell format

Why? If it's a cell array of scalar, a matrix is a lot more efficient.

There are several ways to do this.

1) convert to matrix, replace and convert back to cell array:

tmp = cell2mat(a);
tmp(tmp == E) == D;
a = num2cell(tmp)

2) use cellfun:

a(cellfun(@(elem) elem == E, a)) = {D}

[Guillaume]

Aleksandar comment as an answer copied here: Guillaume, thank you, just a couple a few clarifications please. with this I can change the tmp

tmp = cell2mat(a(:,3)); %I take the third column 
tmp(tmp=='E')='D'; 
tmp = num2cell(tmp);

Now the tmp column contains only A, B, C and D, and is still in a cell format. But how should I now revert it in my matrix 'a' (it was a third column)? As I want to use 'a' matrix in transprob function. (The first and second column are other information (such as ID and date).). PS the cellfun example is not clear to me?

Sorry, I missed that a was the whole cell array, not just the column, the proper code would be:

tmp = cell2mat(a(:, 3));
tmp(tmp == E) == D;
a(:, 3) = num2cell(tmp); %put it back where it came from

And with cellfun:

a(cellfun(@(elem) elem == E, a(:, 3)), 3) = {D}

What the cellfun does is go over each element of the cell array passed to it (in this latter case a(:, 3)) and pass it to the anonymous function:

@(elem) elem == E

This function takes one argument elem, and compare it to E. Therefore it returns a boolean true (1) of false (0). Thus the result of the cellfun is a logical array which tells you which row of a to replace with {D}.

Answer 2

[Aleksandar]

Guillaume, thank you, just a couple a few clarifications please

with this I can change the tmp

tmp = cell2mat(a(:,3)); %I take the third column; tmp(tmp=='E')='D'; tmp = num2cell(tmp); Now the tmp column contains only A, B, C and D, and is still in a cell format. But how should I now revert it in my matrix 'a' (it was a third column)? As I want to use 'a' matrix in transprob function. (The first and second column are other information (such as ID and date).)

PS the cellfun example is not clear to me?