Question

How can I determine the relative frequency of a value in a MATLAB vector?

vector = [ 2 2 2 2 1 1 1 2 2 1 1 1 2 2 2 2 1 2 ];

What function will return the number of occurrences of each unique element?

Answer 1

You can use unique in combination with histc to get the relative frequency.

A=[1,2,3,1,2,4,2,1]; %#an example vector
unqA=unique(A);

This gives the unique elements as unqA=[1,2,3,4]. To get the number of occurances,

countElA=histc(A,unqA); %# get the count of elements
relFreq=countElA/numel(A);

This gives countElA=[3,3,1,1] and relFreq=[0.3750, 0.3750, 0.1250, 0.1250], which is the relative frequency of the unique elements. This will work for both integers and floating points.