# Array multiplicities via sparse

Multiplicities of array elements can be efficiently computed using `sparse`

.
I’ve found this elegant solution in an old Newsgroup thread.

```
% generate some data
A = randi(10,1,100);
% construct the sparse matrix
S = sparse(A,1,1);
% get unique elements and multiplicities
[uA,~,mult] = find(S);
```

```
mult =
(1,1) 8
(2,1) 15
(3,1) 11
(4,1) 5
(5,1) 10
(6,1) 6
(7,1) 10
(8,1) 13
(9,1) 13
(10,1) 9
```

This method is faster than other solutions – almost twice as fast as `histc`

.

```
% test array: 2000 random integers from the set 1:1000
% 1000 iterations
Elapsed time is 0.228704 seconds. % histc
Elapsed time is 1.838388 seconds. % bsxfun
Elapsed time is 0.128791 seconds. % sparse
```