max value from particular set of rows and columns

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Ace_ventura 2015-3-8

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https://ww2.mathworks.cn/matlabcentral/answers/182140-max-value-from-particular-set-of-rows-and-columns

评论： Image Analyst 2015-3-8

Guys, I have a 12X40 matrix. I want to search for the max value but in certain rows and columns. Say, I want to search for max in first three rows and last three rows and column number 2 5 8 14 16 and35. It should pick the max. from these locations only. I tried a=[1 2 3 10 11 12] b=[2 5 8 14 16 35] c=max(max(matrix(a,b))

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Answer 1

Image Analyst 2015-3-8

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https://ww2.mathworks.cn/matlabcentral/answers/182140-max-value-from-particular-set-of-rows-and-columns#answer_170549

编辑：Image Analyst 2015-3-8

在 MATLAB Online 中打开

Try this:

matrix = rand(12, 40) % Sample data
a=[1 2 3 10 11 12]
b=[2 5 8 14 16 35] 
% Extract only the rows we care about
subMatrix = matrix(a, :);
% Extract only the columns we care about
subMatrix = subMatrix(:, b)
% Find the max in what's left:
theMax = max(subMatrix(:))

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Ace_ventura 2015-3-8

I got the answer..Thanks for replying Image Analyst.

Image Analyst 2015-3-8

Well, yes it should have been the same but you said it didn't work, so in the cases where the obvious method does not work, I break it up into smaller parts, sub-expressions, to make sure each sub-step works properly, so that's what I did. I later ran your code and found that it gave the same answer, so I'm not sure what went wrong.

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