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C Zeng

How to make combinations of given condition?

Asked by C Zeng
on 28 Dec 2012

Hi, all,

For example, if I want to make all combination of 5-dim vectors have only 2 two's, other entries are all 0. Is there a command in Matlab can do it? That is 22000 20200 20020 20002 02200 02020 02002 00220 00202 00022




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2 Answers

Answer by Andrei Bobrov
on 28 Dec 2012
Edited by Andrei Bobrov
on 28 Dec 2012
 Accepted answer
k = dec2bin(0:sum(pow2(0:4)))-'0';
out = 2*k(sum(k,2) == 2,:);

  1 Comment

C Zeng
on 28 Dec 2012

Andrei, thanks, can you explain?

Actually I want all other entries to be 1. Is there a way to do it easily?

I tried your code, it works here though not understood here. :-(

Answer by Roger Stafford
on 28 Dec 2012

This is a problem for matlab's 'nchoosek' function.

  1 Comment

C Zeng
on 1 Jan 2013

Thanks, got it!

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