Generate 3 random number that sum to 1 in R

Question

I am hoping to create 3 (non-negative) quasi-random numbers that sum to one, and repeat over and over.

Basically I am trying to partition something into three rand

Answer 1

I guess it depends on what distribution you want on the numbers, but here is one way:

diff(c(0, sort(runif(2)), 1))

Use replicate to get as many sets as you want:

> x <- replicate(5, diff(c(0, sort(runif(2)), 1)))
> x
           [,1]       [,2]      [,3]      [,4]       [,5]
[1,] 0.66855903 0.01338052 0.3722026 0.4299087 0.67537181
[2,] 0.32130979 0.69666871 0.2670380 0.3359640 0.25860581
[3,] 0.01013117 0.28995078 0.3607594 0.2341273 0.06602238
> colSums(x)
[1] 1 1 1 1 1