Count distinct array values
I've searched in forums and faq for this but can't find anything useful.
It's a quick one, I'm pretty sure there's an easy way for doing this (one function most likely);
I have an array (for example):
keys[1, 12, 13, 14, 15, 17, 33, 34, 35, 8, 16, 28, 1, 14, 28, 36]
Now I would like to count how many times each array value is in the array. In this case I need to display only the keys that occur twice in the array (so: 1 and 14).
Is there an easy way for doing this? Thanks very much in advance.