runif() is not uniform [duplicate]

Question

I'm writing a roulette simulator and I stuck just on the beginning. I wanted to draw integer from 0 to 36, so I used runif(). I noticed that 0's are outstanding. Have a look:

n=1000000
x=floor(runif(n,0,37))
hist(x,breaks=37)

To remove "0's" i wrote:

n=1000000
x=floor(runif(n,0,37)*100)/100
hist(x,breaks=37)

What gave me

And my question is why it works?

Answer 1

No, it's not a problem with runif.

Try this instead: plot(density(x))

and you see the distribution is smooth

the issue is with where the breaks in your histogram are being placed, and that there's a fencepost problem at work. Histogram is not the best visualization tool for this, because basically the breaks have to line up perfectly.