MATLAB: How to count the followed occurrences of each element in a vector in MATLAB

followedoccurrencesvector

Hi, I want to count the number of followed occurrences of each element in a vector.
So if my input is
x = [1 1 1 2 2 1 1 2 5 5]
I need an output
y = [1 2 1 2 5;3 2 2 1 2] How do I do this?

Best Answer

Judicious use of diff solves this easily:
x = [1 1 1 2 2 1 1 2 5 5];
f = [find(diff(x)),numel(x)];
y(2,:) = [f(1),diff(f)];
y(1,:) = x(f);
which generates this output:
>> y =
      1   2   1   2   5
      3   2   2   1   2
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