Number of times two numbers appear together

Hi,

I have an array A = [1 3 2 4 3 4 3 2 1 1 3 2 4 3 3 2].

How can I count the number of time the number 2 occurs after 1, the number of times the number 3 occurs after 1, and the number of times the number 4 occurs after 1?

Any help would be appreciated.

Thanks,

DB

Answer 1

[Stephen23]

>> A = [1,3,2,4,3,4,3,2,1,1,3,2,4,3,3,2];

Method one: basic indexing and nnz:

>> nnz(A(1:end-1)==1 & A(2:end)==2)
ans =  0
>> nnz(A(1:end-1)==1 & A(2:end)==3)
ans =  2
>> nnz(A(1:end-1)==1 & A(2:end)==4)
ans =  0

Method two: strfind:

>> nnz(strfind(char(A),char([1,2])))
ans =  0
>> nnz(strfind(char(A),char([1,3])))
ans =  2
>> nnz(strfind(char(A),char([1,4])))
ans =  0