# Rand-array-iid

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A rust crate to create arrays whose elements are independently identically distributed.

## Install

```
[dependencies]
rand-array-iid = "0.1.0"
```

## Examples

### An array of normally distributed scalars
```rust
use rand_array_iid::IIDDistr;
use rand_distr::Distribution;
use rand_distr::StandardNormal;
let distr = IIDDistr::new(StandardNormal);
let mut rng = rand::thread_rng();
// Each of x element is distributed according to StandardNormal.
let x : [f64; 10] = distr.sample(&mut rng);
```

### An array of 3D vectors sampled from the unit sphere
```rust
use rand_array_iid::IIDDistr;
use rand_distr::Distribution;
use rand_distr::UnitSphere;
let distr = IIDDistr::new(UnitSphere);
let mut rng = rand::thread_rng();
// Each of x element is sampled uniformly from the surface of the 3D unit sphere.
let x : [[f64; 3]; 10] = distr.sample(&mut rng);
```

## Why only arrays?

Collections such as `Vec` that implement `std::iter::FromIterator` bear
no information on their size in their type, hence the distribution would have
to be restricted to a given size. They can also be sampled as follow:

```rust
use rand_distr::Distribution;
use rand::Rng;
fn sample_iid<D,R, Col>(dist: D, rng: &mut R, n: usize) -> Col
where
    R: Rng + ?Sized,
    Col: std::iter::IntoIterator,
    Col: std::iter::FromIterator<<Col as std::iter::IntoIterator>::Item>,
    D: Distribution<<Col as std::iter::IntoIterator>::Item>,
{
    dist.sample_iter(rng).take(n).collect()
}
```