# How to find unique combinations between two columns in a cell array

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012786534 on 1 Sep 2019
Commented: 012786534 on 2 Sep 2019
Hi,
I am trying to find all the unique combinations between two columns in a cell array so I can identify if a given sensor has different numbers associated to it. The code below almost works: it does identify that there two numbers associated to sensor2 (98 and 97) but it does not identify that there are two numbers associated to sensor3 (also 98 and 97). The problem comes from the fact that the numbers are not necessarily unique (which can be confusing). It is the combination of the 2 columns that is unique, not the number (99, 98, 97).
So how can I fix the code below so it identifies if a given sensor has more than one number associated to it?
test = {'sensor1', 'sensor1', 'sensor2', 'sensor2', 'sensor3', 'sensor3'; '99' '99' '98' '97' '98' '97'}';
[~, k] = unique(test(:, 2), 'stable')
info = test(k, :);
if numel(info(:, 1)) ~= numel(unique(info(:, 1)))
[x, ~, y] = unique(info(:, 1));
z = hist(y, unique(y));
duplicated_sensor = x(z > 1);
fprintf('Warning! The serial number is not unique for the following sensor: %s\n', duplicated_sensor{:})
else
fprintf('The serial numbers are unique for all sensors')
end
Thank you,

Andrei Bobrov on 1 Sep 2019
Edited: Andrei Bobrov on 1 Sep 2019
test = {'sensor1', 'sensor1', 'sensor2', 'sensor2', 'sensor3', 'sensor3';
'99' '99' '98' '97' '98' '97'}'
T = cell2table(test);
T.test2 = str2double(T.test2 );
out = varfun(@(x)x(:)',T,'GroupingVariables','test1');

#### 1 Comment

012786534 on 2 Sep 2019
Hello Mr. Bobrov,
I could modify your answer to it make it work. Like so:
test = {'sensor1', 'sensor1', 'sensor2', 'sensor2', 'sensor3', 'sensor3';
'99' '99' '98' '97' '98' '97'}'
T = cell2table(test);
T.test2 = str2double(T.test2 );
out = varfun(@(x)x(:)',T,'GroupingVariables','test1');
for i = 1 : height(out)
j = out(i,:);
if length(unique(j.Fun_test2(1, :))) > 1
fprintf('Warning! The serial number is not unique for %s\n', j.test1{1, :})
else
fprintf('The serial number is unique for %s\n', j.test1{1, :}')
end
end
Thank you