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How to convert a cell array to a compatible matrix?

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Nandha Kumar
Nandha Kumar on 16 Jul 2021
Commented: Nandha Kumar on 17 Jul 2021
I have a cell array which is filled with matrices of varying size, could you help me to convert it to matrix with filling zeros at in between columns,
in this case the matrix size is ought ot be 41x 41 of double type.
  1 Comment
KSSV
KSSV on 16 Jul 2021
Fill the empty cells with appropriate zero matrices and use Cell2mat.

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Accepted Answer

Jan
Jan on 16 Jul 2021
Edited: Jan on 16 Jul 2021
CC = {rand(9,9), rand(5,4), rand(5,4), rand(6,4), rand(6,4), rand(8,4), rand(8,4), rand(9,4), rand(9, 4); ...
rand(4,5), rand(4,4), [], [], [], [], [], [], []; ...
[], [], rand(4,4), [], [], [], [], [], []; ...
rand(4,6), [], [], rand(4,4), [], [], [], [], []; ...
[], [], [], [], rand(4,4), [], [], [], []; ...
rand(4,6), [], [], [], [], rand(4,4), [], [], []; ...
[], [], [], [], [], [], rand(4,4), [], []; ...
rand(4,6), [], [], [], [], [], [], rand(4,4), []; ...
[], [], [], [], [], [], [], [], rand(4,4)};
C = CC;
S1 = cellfun('size', C, 1);
maxS1 = max(S1, [], 2);
S2 = cellfun('size', C, 2);
maxS2 = max(S2, [], 1);
for i2 = 1:size(C, 2)
for i1 = 1:size(C, 1)
X = C{i1, i2};
if size(X, 1) < maxS1(i1) || size(X, 2) < maxS2(i2)
X(maxS1(i1), maxS2(i2)) = 0;
C{i1, i2} = X;
end
end
end
Result = cell2mat(C);
Cheaper:
C = CC;
S1 = cellfun('size', C, 1);
maxS1 = max(S1, [], 2);
S2 = cellfun('size', C, 2);
maxS2 = max(S2, [], 1);
Result2 = zeros(sum(maxS1), sum(maxS2));
c1 = 1;
for i1 = 1:size(C, 1)
c2 = 1;
for i2 = 1:size(C, 2)
X = C{i1, i2};
Result2(c1:c1 + size(X,1) - 1, c2:c2 + size(X,2) - 1) = X;
c2 = c2 + maxS2(i2);
end
c1 = c1 + maxS1(i1);
end
isequal(Result, Result2)
ans = logical
1
It took some tome to create some test data as input. Please care for providing some code, which creates your input data, to make answering as easy as possible.
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