How to select a random sample without replacement with imposed condition?

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Christian
Christian 2015-10-24
评论： Christian 2015-10-24
Hi,
I'd like to draw a random sample from my population. My population is a vector x of size (N x 1). My sample should satisfy
sum(x(sample)) = 0.7*sum(x);
So I do not care how many observations I draw from the sample, but I just want to make sure that the resulting sample covers 70 percent of total x in terms of value, not in terms of number.
Thanks, Christian
  2 个评论
Christian
Christian 2015-10-24
Good point. Let's say at least 0.7, but as close as possible to 0.7. So stop sampling as soon as the sum is equal or greater than 0.7.

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采纳的回答

Walter Roberson
Walter Roberson 2015-10-24
rp = randperm(N);
loc = find( cumsum(x(rp)) >= 0.7 * sum(x), 1, 'first');
samps = x(rp(1:loc));

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