How to find all the even numbers in a vector?

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Tin Nguyen 2015-8-15

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https://ww2.mathworks.cn/matlabcentral/answers/233941-how-to-find-all-the-even-numbers-in-a-vector

评论： Image Analyst 2015-8-15

Say we have a vector x=[ 1 1 2 2 2 2 3 3 3 3 4 4 4 ] and I want to find all the even numbers but subtract is by 1 so that the vector will only contain odd numbers. How would I do that?

回答（1 个）

Image Analyst 2015-8-15

1
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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/233941-how-to-find-all-the-even-numbers-in-a-vector#answer_189387

在 MATLAB Online 中打开

Try this:

% Create sample data.
x = [ 1 1 2 2 2 2 3 3 3 3 4 4 4 ] 
% Find indices where x is even:
evenIndices = rem(x, 2) == 0
% Extract only the even numbers into a new vector.
allTheEvenNumbers = x(evenIndices)
% Now subtract 1 from that.
allTheEvenNumbers = allTheEvenNumbers - 1

In the command window, you'll see:

x =
     1     1     2     2     2     2     3     3     3     3     4     4     4
evenIndices =
     0     0     1     1     1     1     0     0     0     0     1     1     1
allTheEvenNumbers =
     2     2     2     2     4     4     4
allTheEvenNumbers =
     1     1     1     1     3     3     3

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Tin Nguyen 2015-8-15

Thanks that was exactly what I was looking for! And yes it is a part of a homework assignment but this particular code is just a small part to a larger code.

Image Analyst 2015-8-15

Please mark the best answer as "Accepted" when you're done with a discussion. Also, next time, tag the post as "homework" so we can answer appropriately and don't put you at risk of your instructor or plagiarism detectors some schools use finding out that you just had us solve the problem. We wouldn't want you to get in trouble.

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