# Command to reshape matrix diagonally

3 views (last 30 days)
fr_sk on 8 Apr 2016
Commented: Andrei Bobrov on 8 Apr 2016
Hi, i'd like to transform
X = 1 100 40
2 107 30
3 90 50
4 120 60
into
Y = 1 100 40 3 90 50
2 107 30 4 120 60
I thought
Y = reshape(X,2,6)
would do the trick but it didn't give me the matrix I was looking for.
Any quick ideas will be appreciated.
Thanks!

Andrei Bobrov on 8 Apr 2016
Edited: Andrei Bobrov on 8 Apr 2016
% X - array with size [5541888 x 7]
% m2 - number of rows in second array, m2 = 1536
[~,n] = size(X);
out = reshape(permute(reshape(X',n,m2,[]),[1 3 2]),[],m2)';
or
[m,n] = size(X);
a = mat2cell(X,m2*ones(m/m2,1),n);
out = [a{:}];
fr_sk on 8 Apr 2016
This is the perfect solution, it works like charm!!! Thank you so much!
Just so I understand what you did: What does [1 3 2] do in this case? Also why X' instead of X ?
Andrei Bobrov on 8 Apr 2016
rewrite on separate commands:
[~,n] = size(X);
a = reshape(X',n,m2,[]);
b = permute(a,[1 3 2]);
out = reshape(b,[],m2)';

Rick Rosson on 8 Apr 2016
Y = [ X(1:end/2,:) X(end/2+1:end,:) ];
fr_sk on 8 Apr 2016
Wow, thanks a lot for the fast response. This works very well for this example. My actual dataset has the dimensions of 5541888 x 7, which I want to stack according to your method to obtain a 1536 X 25256 matrix.
I wanted to apply your idea, but then I realized that I have to enter the code for each column manually. Do you think there is a way to do it for these dimensions?