MATLAB Answers

Unique values in cell array

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Charms on 14 Apr 2020
Commented: Star Strider on 14 Apr 2020
Hi, I have a cell array and would like to find the unique values (by row) in the cell array. Each row has a variable number of numbers. However, in the documentation, unique function does not support cell array by row. Is there a way i can get past this? Thanks!

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Geoff Hayes
Geoff Hayes on 14 Apr 2020
Charms - do you mean that you want to find the unique integers from the two columns in a single row?

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Accepted Answer

Star Strider
Star Strider on 14 Apr 2020
The cells in ‘locations’ have from 3 to 10 columns, so comparing all of them by rows is not possible.
Likely the best you can do is to get the unique rows of the elements in ‘locations’ that share the same number of columns.
This code does that:
D = load('locations.mat');
locations = D.locations;
for k = 1:size(locations,1)
rowc{k,:} = [locations{k,:}];
rowlen(k,:) = numel(rowc{k});
[lenv,~,ix] = unique(rowlen);
eqcol = accumarray(ix, (1:numel(rowlen))', [], @(x){x});
for k = 1:numel(lenv)
rowm = cell2mat(rowc(eqcol{k}));
U{k,:} = unique(rowm, 'rows');
To see the result, for example for the 4-column cells:
Rows4 = cell2mat(rowc(eqcol{2}))
Check4 = U{2}
with ‘Rows4’ being the original cell array of those combined cells, and ‘Check4’ being the unique rows.


Dave on 14 Apr 2020
Maybe I misunderstand but doesn't the following meet your requirements
B = cellfun(B = cellfun(@unique, locations(:), 'UniformOutput', false))
Star Strider
Star Strider on 14 Apr 2020
@Dave — First, that is definitely incorrect MATLAB code. It is not possible to run it.
Second, Charms wants to see if the rows are unique, that being the whole point.
So I seriously doubt that it would.

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