Problem with find and logical array

2014 6 6
3 个回答
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更新时间：2014 6 6
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0 个投票

Hi,
I have a matrix with the values : A = [260,343; 344,433; 434,530; 531,631; 632,723];
where A(:,1) is the lower range and A(:,2) = upper range for each row. I am trying to find the index of A where a number may exist within the upper and lower range.
For ex. I tried B = (443 > A(:,1) & A(:,2) > 443) to check in which row the number 443 would lie, but got the ans as 0, even though when B comes as = [0,0,1,0,0]. I performed index = find(B),
I am probably doing something stupid. What am I doing wrong?
Thanks, Urvashi

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José-Luis
José-Luis 2014-6-6
I don't understand. The function seems to do exactly what you want it to do, according to your description.
Urvashi
Urvashi 2014-6-6
I know. I will download 'find' again. May be it's a problem with my function
Geoff Hayes
Geoff Hayes 2014-6-6
What do you mean by "download 'find' again"? Are you using a different version of find from the built-in one?

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Sara
Sara 2014-6-6
编辑：Sara 2014-6-6

0 个投票

You could do:
B = find(443 > A(:,1) & A(:,2) > 443);
B is the row or rows where the condition is satisfied.

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Urvashi
Urvashi 2014-6-6
I did that too, and still got the answer as B = 0. There might be something wrong with the function 'find' in my version. I should probably download it again.
Sara
Sara 2014-6-6
Yeah, could be, because everybody here is getting the right result.

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更多回答（2 个）

Image Analyst
Image Analyst 2014-6-6

0 个投票

I don't see any problem:
A = [260,343; 344,433; 434,530; 531,631; 632,723]
targetValue = 443
logicalRowsInRange = (targetValue > A(:,1) & A(:,2) > targetValue)
rowInRange = find(logicalRowsInRange)
A =
260 343
344 433
434 530
531 631
632 723
targetValue =
443
logicalRowsInRange =
0
0
1
0
0
rowInRange =
3
Urvashi
Urvashi 2014-6-6
编辑：Urvashi 2014-6-6

0 个投票

Yeah, thanks a lot. It worked. I had missed a ) in one of my previous statements of find, so find ended up being an empty matrix. And I didn't realize that the variable find was generated as there was a huge list of variables being generated during the program run.
My bad. Really, my bad.

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