I have been trying to do generate non-uniform random distribution with Rust and Rand crate, but I wonder if there is an easy way to do this.

suppose I have a vec:

`let s =vec![0.8;0.1;0.1]`

I want to generate a number from a set, maybe {0,1,2}, so that 80%, it will be 0, 10% it will be 1 and 10% it will be 2, just like the random distribution from the distribution vec.

Seem straightforward but I am unaware if the Rand crate would allow me to do so. I have to create my own function like this:

```
fn non_uniform_rand(distribution_vec:&Vec<f64>)->usize{
let mut rng= rand::thread_rng();
let mut sum=0.0;
for i in 0..distribution_vec.len(){
sum+=distribution_vec[i];
}
assert_eq!(sum, 1.0);
for i in 0..distribution_vec.len()-1{
let random_number=rng.gen_range(0..1000);
if random_number < (distribution_vec[i] * 1000.0) as i32{
return i
}
}
distribution_vec.len()-1
}
```

It works but not really elegant. I am looking for anything built into Rand Crate.

Thank you.