Choose specific number with probability

Question

How can one choose a number with a specific probability p?

Say we must choose between {0, 1} and the probability p stands for choosing 1.

So when p=0.8 we choose 1 with 80% and 0 with 20%.

Is there a simple solution in R for this?

Answer 1

Examine the sample function.

set.seed(1)
sample(c(0,1), size=12, replace=TRUE, prob=c(0.2,0.8))

1 1 1 0 1 0 0 1 1 1 1 1 

 sample takes a sample of the specified size from the components of x and in sample, 
and the argument prob in sample is a vector of probability weights for obtaining the elements of the sampled vector.