Counting certain values from an array

2016 9 22
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更新时间：2016 9 22
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Suppose we have an array r=(2,2,2) filled with zeros and ones. How to count up how many zeros and how many ones do we have?

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Image Analyst
Image Analyst 2016-9-22

1 个投票

Try this:
numOnes = sum(r(:))
numZeros = numel(r) - numOnes

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Vadim Tambovtsev
Vadim Tambovtsev 2016-9-22
No, my array in more complicated. Array (m,n,k), contans "a" and "b" values. How many "a" and "b" are there?
Image Analyst
Image Analyst 2016-9-22
编辑：Image Analyst 2016-9-22
You could have sped this along by two hours by saying that first instead of saying the array is "filled with zeros and ones". So to count the number of a's and b's:
numA = length(find(r==a));
numB = length(find(r==b));
There are other ways, but this is fairly simple and compact.
Vadim Tambovtsev
Vadim Tambovtsev 2016-9-22
编辑：Image Analyst 2016-9-22
quality control:
dd=[ 3 7; 4 5]
num7=sum(find(dd==7))
output:
num7= 3
Why is it 3? isn't it supposed to be 1, because there is 1 "7" in the array?
Image Analyst
Image Analyst 2016-9-22
Use length() instead of sum().

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