How can I randomly sample binomial thing?

Question

For example, I want to randomly line the 0, 1 (50% respectively) 10 times. So, there should be five "0" and five "1".

But, when I used:

rbinom(10,1,0.5)

sometimes, it generates four "0" and six "1".

I noticed that the sample() function has also this issue.

There should be five "0" and five "1", and the order should be at random.

What you are asking for is a permutation, not the binomial distribution. — user2554330, Mar 20 '22 at 21:59

score 6 · Accepted Answer · answered Mar 20 '22 at 21:16

6

sample will shuffle a vector randomly. So sample(rep(c(0,1),5)) is what you need.

answered Mar 20 '22 at 21:16

George Savva

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score 5 · Answer 2 · answered Mar 20 '22 at 21:16

5

You need to use sample(), but this way:

b <- c(rep(0, 5), rep(1, 5))
sample(b)
#  [1] 1 0 1 1 0 0 1 0 0 1
sample(b)
#  [1] 0 1 1 1 0 1 0 0 0 1
sample(b)
#  [1] 0 0 0 1 1 1 0 1 0 1
sample(b)
#  [1] 0 1 0 0 1 0 1 1 0 1

answered Mar 20 '22 at 21:16

dcarlson

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score 3 · Answer 3 · answered Mar 20 '22 at 21:22

3

A shortcut would be:

sample(10) %/% 6
#> [1] 0 0 0 1 1 0 0 1 1 1

answered Mar 20 '22 at 21:22

Allan Cameron

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score 3 · Answer 4 · answered Mar 20 '22 at 21:57

3

We can use bitwAnd + sample

bitwAnd(sample(10), 1)

answered Mar 20 '22 at 21:57

ThomasIsCoding

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How can I randomly sample binomial thing?

4 Answers4