cell to double with mismatched dimensions

Input:

a = cell(3,1);
a{1,1} = [1 2 3];
a{2,1} = [1 2 3 4];
a{3,1} = [1 2 3 4 5];

Desired output:

b = [[1 2 3 0 0];[1 2 3 4 0];[1 2 3 4 5]];

What would be the best way to get this output from this input?

Answer 1

[Geoff Hayes]

Jonathan - one way would be to use cellfun to apply a function to each element of your cell array padding each with zeros so that all arrays are of the same length. For example, we can get the maximum length as

 maxLength = max(cellfun(@(x)length(x),a));

We would then use cellfun again to pad the arrays with zeros using repmat (which just repeats a matrix) as

 aPadded = cellfun(@(x)[x repmat(0,1, maxLength - length(x))],a,'UniformOutput',false);

Finally, use cell2mat to convert your cell array into a matrix as

 b = cell2mat(aPadded);

Try the above and see what happens!

[Jonathan Soucy]

Hi Geoff, that worked very well. Thank you! I also came up with this solution which is actually very similar to what you came up with

    a_max = max(cellfun(@length,a));
    b = zeros(length(a),a_max);
    for m = 1:length(a)
        b(m,:) = [a{m,1} zeros(1,(a_max-length(a{m,1})))];
    end

I'm not sure which option is best, but I guess it is good to have options