Finding largest data from table

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Sebastian Daneli
Sebastian Daneli on 15 Nov 2021
Edited: Seth Furman on 16 Nov 2021
Lets say that I have a table containing three matricies of different lengths.
X1=[9 6 9 0;3 2 7 0];
X2=[0 2;4 0];
X3=[3 1 2; 8 9 7];
X=table(X1,X2,X3)
X = 2×3 table
X1 X2 X3 ________________ ______ ___________ 9 6 9 0 0 2 3 1 2 3 2 7 0 4 0 8 9 7
How can i I find the longest one? Is there a way to find more then one matrix of a specific lenght? Lets say the ones that are the longest.
  1 Comment
Chunru
Chunru on 15 Nov 2021
Show what the data you have by giving a minimum example.

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Accepted Answer

Chunru
Chunru on 15 Nov 2021
Edited: Chunru on 15 Nov 2021
X1=[9 6 9 0;3 2 7 0];
X2=[0 2;4 0];
X3=[3 1 2; 8 9 7];
X4 = X1;
X=table(X1,X2,X3,X4)
X = 2×4 table
X1 X2 X3 X4 ________________ ______ ___________ ________________ 9 6 9 0 0 2 3 1 2 9 6 9 0 3 2 7 0 4 0 8 9 7 3 2 7 0
len = table2array(varfun(@(x) size(x, 2), X));
% max will find 1 entry only
[lmax, idx] = max(len)
lmax = 4
idx = 1
% if you want multiple entries
idxall = find(len == lmax)
idxall = 1×2
1 4
  2 Comments
Seth Furman
Seth Furman on 16 Nov 2021
Edited: Seth Furman on 16 Nov 2021
The only thing I would add is that
@(x) size(x, 2)
ans = function_handle with value:
@(x)size(x,2)
can be replaced with
@width
ans = function_handle with value:
@width
since the width function returns the number of variables in a table or the number of columns in an array.
e.g.
X1 = [9 6 9 0;3 2 7 0];
X2 = [0 2;4 0];
X3 = [3 1 2; 8 9 7];
X4 = X1;
X = table(X1,X2,X3,X4)
X = 2×4 table
X1 X2 X3 X4 ________________ ______ ___________ ________________ 9 6 9 0 0 2 3 1 2 9 6 9 0 3 2 7 0 4 0 8 9 7 3 2 7 0
varfun(@width, X, "OutputFormat", "uniform")
ans = 1×4
4 2 3 4

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