Count the number of times a value occurs in a specific of an array

Given a array, is there any way to count the number of times a value occurs within a specific row of that array?

For example, if I have a array:

 A=[1,2,5,2,3,4,2; 4,2,1,5,3,2,3; 1,4,2,3,2,2,1];

I want to know how many times the value '2' occurs in the second row

Thanks

Answer 1

[Azzi Abdelmalek]

A=[1,2,5,2,3,4,2; 4,2,1,5,3,2,3; 1,4,2,3,2,2,1]
sum(A(2,:)==2)

%or

nnz(A(2,:)==2)

[Tyler]

Thanks Azzi!

If I had the same problem, but I wanted to determine how many values were between a certain range, (ie. between 2 and 4) how would I do that?

[Image Analyst]

Tyler, you can use histc(). See my answer or Star's answer.

Answer 2

[Image Analyst]

In general, you can use histc() to find the counts for all of the numbers in one shot:

A=[1,2,5,2,3,4,2; 4,2,1,5,3,2,3; 1,4,2,3,2,2,1];
edges = unique(A)
counts = histc(A(:), edges)

In the command window:

edges =
     1
     2
     3
     4
     5
counts =
     4
     8
     4
     3
     2

[KARANAM ANILBABU]

Thanks really helpful.

Answer 3

[Geoff Hayes]

Try the following to find the number of times '2' occurs in the second row

 length(find(A(2,:)==2))

[Matz Johansson Bergström]

or the shorter and more to the point

sum( A(2,:)==2 )