# How to convert a cell to matrix?

2 views (last 30 days)
SM on 16 Jul 2020
Edited: the cyclist on 16 Jul 2020
Example:
A={[1 3 4];
[2 5 6 4];
[2 6 8 9 5 6];
[3 6 5 4 1]}
I know it is not possible by using
B=cell2mat(A);
as it has different array size.
We may use NaN to follow concatenation rules.
How can I do that?
Once converted to matrix, How can I come back to same cell from the matrix?
the cyclist on 16 Jul 2020
For that input A, what exactly do you want the output to be? For example, do you want
B=[1 3 4 NaN NaN NaN;
2 5 6 4 NaN NaN;
2 6 8 9 5 6;
3 6 5 4 1 NaN]
?
SM on 16 Jul 2020
Yes, First i want what you have written. Second, I want to come back from B to A.

Akira Agata on 16 Jul 2020
Edited: Akira Agata on 16 Jul 2020
% Convert to numeric array
maxLen = max(cellfun(@numel,A));
A = cellfun(@(x)[x, NaN(1,maxLen - numel(x))],A,'UniformOutput',false);
B = cell2mat(A);
% Back to cell array
A2 = mat2cell(B,ones(1,size(B,1)));
A2 = cellfun(@rmmissing,A2,'UniformOutput',false);

the cyclist on 16 Jul 2020
Edited: the cyclist on 16 Jul 2020
Here is one straightforward way:
% Original data
A={[1 3 4];
[2 5 6 4];
[2 6 8 9 5 6];
[3 6 5 4 1]};
%%%%%% Convert to B
% Get number of rows of A, and the maximum vector length within A
M = numel(A);
N = max(cellfun(@numel,A));
% Preallocate B to the correct size
B = nan(M,N);
% Fill each row of B with the corresponding row of A
for im = 1:M
Arow = A{im};
B(im,1:numel(Arow)) = Arow;
end
%%%%%% Convert B back to A
% Preallocate A2 to the correct number of rows
M2 = size(B,1);
A2 = cell(M2,1);
% Fill A2 with the non-NaN elements of B
for im = 1:M2
A2{im} = B(im,~isnan(B(im,:)))
end
% Show that they're identical
isequal(A,A2)