Extract upper diagonal half in a large cell array and replace rest with NaN

Hello,

I have a very large cell array and want to select upper diagonal from it and replace the rest with NaNs. For example, if I have a 5x5 cell array, I'd like to get a result similar to;

1,1  1,2  1,3  1,4  1,5
2,1  2,2  2,3  2,4  NaN
3,1  3,2  3,3  NaN  NaN
4,1  4,2  NaN  NaN  NaN
5,1  NaN  NaN  NaN  NaN

Answer 1

[Azzi Abdelmalek]

A=[1 2 3 4; 5 6 7 8; 9 10 11 12;13 14 15 16]
ii=ones(size(A))
idx=rot90(tril(rot90(ii)),-1);
A(~idx)=nan

[SMA]

tril and triu does not work on cell arrays, otherwise this would have been simple. I have a very large cell array with each cell containing numeric arrays of different sizes.

[Azzi Abdelmalek]

use cell2mat

[Azzi Abdelmalek]

or without cell2mat

A={1 2 3 4; 5 6 7 8; 9 10 11 12;13 14 15 16}
ii=ones(size(A))
idx=rot90(tril(rot90(ii)),-1);
A(~idx)={nan}

[SMA]

Thank you, that is what I was looking for without loops.