MATLAB: How to assign values to elements with same index from multiple cells

cell arraylinear indexing

I have a cell array with the same-size matrix in each cell, say,
a = cell(2);
[a{:}]=deal(rand(2));
and I want to change the first element of the matrix in each cell to values 1,2,3 and 4 respectively. Something equivalent to
a{:}(1,1) = 1:4;
would be ideal however this syntax doesn't work. Is there any other way?

Best Answer

Matlab is not clever enough to expand inner indexing into outer cells (plus there's no guarantee it would work, some cells may not even have 4 elements). So you have to do it yourself and you don't have a choice but to use a loop:
vals = 1:4;
for idx = 1:numel(a)
  a{idx}(1) = vals(idx);
end
However, if all the matrices are the same dimension, you could simply convert your cell array to a matrix, which then lets you use normal indexing. With your example:
alla = cat(3, a{:});
alla(1, 1, :) = 1:4;
%and if you want it back as a cell array
a = reshape(num2cell(alla, [1 2]), size(a))
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