Generate a vector "b" from an already defined vector "B" several times but taking different elements of "A" each time

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EB
EB 2017-11-27
回答： EB 2017-11-28
I have to generate a vector "b" from an already defined vector "B" but taking different set of values each time. The length of the new vector "b" should be the same each time, but the indices of values that it takes from "B" should be different each time.
Lets say that B = 1x4425. I have to define new vector "b" 15 times but each time its length has to be 1x295. Also the indices of elements of "B" that "b" takes have to be different for each time that "b" is generated, there shouldn't be any repetitions for any of the elements in "b". Also, every time that "b" is generated I have to remember the indices of elements that are taken from "B".
Any advice on how to write this is more than welcome.
Thank you!

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采纳的回答

Jeff Miller
Jeff Miller 2017-11-27
idx=reshape(randperm(4425),15,295);
b = reshape(B(idx(:)),15,295);
The 15 rows of b are the 15 new vectors, and idx holds the index in B of each element in each vector.

更多回答（2 个）

Stephen23
Stephen23 2017-11-27
编辑：Stephen23 2017-11-27
>> B = rand(1,4425);
>> out = B(reshape(randperm(4425),15,295));
Each row of out is a random vector of elements of B. Each element of B appears only once in out.
EB
EB 2017-11-28
Thank you for you answers. Because I needed to remember the indices of the elements that are taken from B, I have accepted the first answer.

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