Is there a non-iterative equivalent of this expression in MATLAB?

The e开发者_开发百科xpression is:

for i=1:n
    X(:,i) = [P{i}(:)];
end

where X is a DxN matrix and P is a cell-array.

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reshape(cat(3,P{:}),[numel(P{1}) n])

Of course, the above solution is just for fun. I would recommend profiling both solutions and only using this one if it has a significant performance advantage.

Maintenance and readability are also very important factors to consider when writing code.

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If you obtained the cell array via mat2cell, you may be wanting to arrange blocks of an image into the columns of an array X. This can be achieved in a single step using the command IM2COL

%# rearrange the large array so that each column of X
%# corresponds to the 4 pixels of each 2-by-2 block
X = im2col(largeArray,[2 2],'distinct');

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You might be able to get away with:

P{1} = [ 1 2; 3 4];
P{2} = [ 7 8; 9 10];
P{3} = [ 11 12; 13 14];
X = [P{:}]

X =

     1     2     7     8    11    12
     3     4     9    10    13    14

Then some sort of reshape() to get to where you want to be.