Function rand::seq::index::sample_weighted

source ·
pub fn sample_weighted<R, F, X>(
    rng: &mut R,
    length: usize,
    weight: F,
    amount: usize
) -> Result<IndexVec, WeightError>
where R: Rng + ?Sized, F: Fn(usize) -> X, X: Into<f64>,
Available on crate features alloc and std only.
Expand description

Randomly sample exactly amount distinct indices from 0..length, and return them in an arbitrary order (there is no guarantee of shuffling or ordering). The weights are to be provided by the input function weights, which will be called once for each index.

This method is used internally by the slice sampling methods, but it can sometimes be useful to have the indices themselves so this is provided as an alternative.

Error cases:

This implementation uses O(length + amount) space and O(length) time.