MATLAB: How to find unique elements in a vector without using unique or find

arrayunique

I have A=randi(100,1,100); How can I find unique values in array and show them without using unique() and find() .

Best Answer

Use an histogram based approach (works only for positive integers)

%get M random numbers from 1 to N
M=10; N=25; 
A=randi(N,1,M)
%find unique values
x=1:N;
unique_vals = x(logical(accumarray(A',1,[N,1])))

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MATLAB: Unique command

x = randi(8,15,1)
a = unique(x)
number_of_frequent = histc(x,a)
out = [a number_of_frequent]

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@andrei:

This does not work because it returns several rows which contain the same element. What I am looking for is a matrix of rows which only contain unique elements. In the above example, this is a single row [1 2 3], but in principle could be much larger. As an example, consider the following:

x = allcomb(1:5, 1:5, 1:5); 
y = unique(sort(x, 2), 'rows');    
y(y(:,1) == y(:,2) | y(:,1) == y(:,3) | y(:,2) == y(:,3), :) = []

Thanks, Dan

[I accidentally hit the accept this answer button. Please disregard.]

Best Answer

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MATLAB: Return all unique rows with unique elements

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