How to count replicates in an array

Question

If you have the following array

a = [1 1 3 4 4 1 1 4 4 4];

I want to get this result

b = [1 3 4 1 4];
c = [2 1 2 2 3];

b is an array with unique adjacent values from a,

c is an array that counts the number of repetition

Is there a way to do this without loops?

What you are asking for is [run length encoding](http://en.wikipedia.org/wiki/Run-length_encoding). This has been asked to death here on StackOverflow. The one I linked to is one of the more popular posts. If you look at Mohsen's answer, simply equate `numCode` with your input array. — rayryeng, May 22 '15 at 17:27

score 1 · Accepted Answer · answered May 22 '15 at 17:27

1

One approach with diff -

b = a([true diff(a)~=0])
c = diff(find([1 diff(a)~=0 1]))

answered May 22 '15 at 17:27

Divakar

1 Answers1