Test different number(values or label) in matrix?

hello, I want to detect different number in matrix?

for exmaple in a matrix:

0 0 0 0 0 0 0; 
3 3 0 0 0 0 0; 
3 3 3 0 0 0 0;
0 0 0 0 4 4 4; 
0 0 5 5 0 0 0;
5 5 5 5 5 0 0;

How can I know the number of different values in this matrix, and index for any elements with same value?

Can I use function 'diff'?

Answer 1

[Paulo Silva]

number of different values, A is your matrix

numel(unique(A))

All code:

a=[0 0 0 0 0 0 0 
3 3 0 0 0 0 0 
3 3 3 0 0 0 0
0 0 0 0 4 4 4 
0 0 5 5 0 0 0
5 5 5 5 5 0 0];

b=unique(a)

for i=2:numel(b)
c=find(a==b(i))';
fprintf('The value %d appears %d times, indices %s\n',b(i),numel(c),num2str(c))
end

[REN]

thanks...

Answer 2

[Matt Fig]

A = [0 0 0 0 0 0 0; 
     3 3 0 0 0 0 0; 
     3 3 3 0 0 0 0;
     0 0 0 0 4 4 4; 
     0 0 5 5 0 0 0;
     5 5 5 5 5 0 0]

U = unique(A);  % Has the unique elements of A.
LU = length(U);  % Has the number of unique elements of A.
[L,I] = histc(A(:).',U) % Has the counts per element and locations.

[REN]

just realize can not accepted two answers at same time?

Thanks Matt Fig!