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problem with randsample when array with one element

4 次查看（过去 30 天）
Jack Ie
Jack Ie 2016-4-3
回答： Aaron Schnydrig 2020-10-6
when vector has one element, the result of randsample is not correct for my problem. It returns a random number from 1 to that element.
for example:
n=[3];
x = randsample(n,1);
randsample returns x=1 or x=2 or x=3
but I want x=3 only

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采纳的回答

Chad Greene
Chad Greene 2016-4-3
Perhaps you want
n = 3;
% get a random index no greater than the length of n:
ind = randsample(length(n),1);
% take a random value from n:
x = n(ind)

更多回答（3 个）

Image Analyst
Image Analyst 2016-4-3
What do you mean by "when vector has one element"??? WHAT vector? randsample will return 1 number randomly chosen from the vector 1 ..... n, which in your case is [1,2,3] so of course x will be either 1, 2, or 3. What did you expect? If you want x to be 3 or n, simply do this
x = n;
Roger Stafford
Roger Stafford 2016-4-3
That's what it is supposed to return. Read the website:
http://www.mathworks.com/help/stats/randsample.html
which states " y = randsample(n,k) returns a k-by-1 vector y of values sampled uniformly at random, without replacement, from the integers 1 to n."
Aaron Schnydrig
Aaron Schnydrig 2020-10-6
The question is quite old, but for the ones finding it over Google (like I did):
The simplest answer would be the following:
x = randsample(repmat(n, 2, 1), 1);
The repmat() function uses every value of your vector twice. Therefore, it will not change the probability of a certain element. However, it will make sure that your vector always has more than one element and is therefore used as a population.

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