How do i select random indicies from an array?

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ME 2015-3-5

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回答： Image Analyst 2015-3-5

I have an array of 10 by 6. is there a way I can randomly select rows from this particular array and everything within it.

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Answer 1

Image Analyst 2015-3-5

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Let's say you have a 10-by-6 matrix m, and you want to select 7 rows at random and make sure there are no repeats. Do this:

m = randi(9, 10,6)
randomRows = randperm(size(m, 1), 7)

randomRows is the array of row numbers , not the actual 6 element rows themselves.

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Answer 2

Joseph Cheng 2015-3-5

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编辑：Joseph Cheng 2015-3-5

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yes, you can perform something like this. Lets say your 10 by 6 array is called A;

then to get the random row(s) you can do

A(randi(10,N,1),:)

where 10 is the number or rows in A (or you can do size(A,1) if you do not want to hard code 10), N is the number of random rows you want to select and the : selects all columns.

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Image Analyst 2015-3-5

Just a watchout: With randi(), it's really random meaning that there is a possibility that the same row might be "chosen" twice or more. If you don't want that (you want, say, 5 rows and all rows to be unique), then use randperm() instead.

ME 2015-3-5

yes I am looking for unique rows Thank you for that. how would I save the randomised array into another array or even get the generated random results to be displayed... sorry I am new to this

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