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

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Tyler
Tyler 2014-7-17
评论： KARANAM ANILBABU 2019-2-10
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

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采纳的回答

Azzi Abdelmalek
Azzi Abdelmalek 2014-7-17
编辑：Azzi Abdelmalek 2014-7-17
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)
  2 个评论
Tyler
Tyler 2014-7-29
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?

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更多回答（2 个）

Image Analyst
Image Analyst 2014-7-17
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
Geoff Hayes
Geoff Hayes 2014-7-17
Try the following to find the number of times '2' occurs in the second row
length(find(A(2,:)==2))

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