Struct iterative_methods::WeightedReservoirSample

pub struct WeightedReservoirSample<I, T> {
    pub reservoir: Vec<WeightedDatum<T>>,
    // some fields omitted
}

Adaptor that reservoir samples with weights

Uses the algorithm of M. T. Chao. WeightedReservoirSample wraps a StreamingIterator, I, whose items must be of type WeightedDatum and produces a StreamingIterator whose items are samples of size capacity from the stream of I. (This is not the capacity of the Vec which holds the reservoir; Rather, the length of the reservoir is normally referred to as its capacity.) To produce a reservoir of length capacity on the first call, the first call of the advance method automatically advances the input iterator capacity steps. Subsequent calls of advance on ReservoirIterator advance I one step and will at most replace a single element of the reservoir. The random rng is of type Pcg64 by default, which allows seeded rng. See https://en.wikipedia.org/wiki/Reservoir_sampling#Weighted_random_sampling, https://arxiv.org/abs/1910.11069, or for the original paper, https://doi.org/10.1093/biomet/69.3.653. Future work might include implementing parallellized batch processing: https://dl.acm.org/doi/10.1145/3350755.3400287

Fields

reservoir: Vec<WeightedDatum<T>>

Trait Implementations

impl<I: Clone, T: Clone> Clone for WeightedReservoirSample<I, T>

fn clone(&self) -> WeightedReservoirSample<I, T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<I: Debug, T: Debug> Debug for WeightedReservoirSample<I, T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<I, T> StreamingIterator for WeightedReservoirSample<I, T> where
    T: Clone + Debug,
    I: StreamingIterator<Item = WeightedDatum<T>>, 

type Item = Vec<WeightedDatum<T>>

The type of the elements being iterated over.

fn advance(&mut self)

Advances the iterator to the next element.

fn get(&self) -> Option<&Self::Item>

Returns a reference to the current element of the iterator.

fn next(&mut self) -> Option<&Self::Item>

Advances the iterator and returns the next value.

fn size_hint(&self) -> (usize, Option<usize>)

Returns the bounds on the remaining length of the iterator.

fn all<F>(&mut self, f: F) -> bool where
    F: FnMut(&Self::Item) -> bool, 

Determines if all elements of the iterator satisfy a predicate.

fn any<F>(&mut self, f: F) -> bool where
    F: FnMut(&Self::Item) -> bool, 

Determines if any elements of the iterator satisfy a predicate.

fn by_ref(&mut self) -> &mut Self

Borrows an iterator, rather than consuming it.

fn chain<I>(self, other: I) -> Chain<Self, I> where
    I: StreamingIterator<Item = Self::Item>, 

Consumes two iterators and returns a new iterator that iterates over both in sequence.

fn cloned(self) -> Cloned<Self> where
    Self::Item: Clone, 

Produces a normal, non-streaming, iterator by cloning the elements of this iterator.

fn count(self) -> usize

Consumes the iterator, counting the number of remaining elements and returning it.

fn filter<F>(self, f: F) -> Filter<Self, F> where
    F: FnMut(&Self::Item) -> bool, 

Creates an iterator which uses a closure to determine if an element should be yielded.

fn filter_map<B, F>(self, f: F) -> FilterMap<Self, B, F> where
    F: FnMut(&Self::Item) -> Option<B>, 

Creates an iterator which both filters and maps by applying a closure to elements.

fn flat_map<J, F>(self, f: F) -> FlatMap<Self, J, F> where
    F: FnMut(&Self::Item) -> J,
    J: StreamingIterator, 

Creates an iterator which flattens iterators obtained by applying a closure to elements. Note that the returned iterators must be streaming iterators.

fn filter_map_deref<B, F>(self, f: F) -> FilterMapDeref<Self, F> where
    F: FnMut(&Self::Item) -> Option<B>, 

Creates a regular, non-streaming iterator which both filters and maps by applying a closure to elements.

fn find<F>(&mut self, f: F) -> Option<&Self::Item> where
    F: FnMut(&Self::Item) -> bool, 

Returns the first element of the iterator that satisfies the predicate.

fn fuse(self) -> Fuse<Self>

Creates an iterator which is “well behaved” at the beginning and end of iteration.

fn inspect<F>(self, f: F) -> Inspect<Self, F> where
    F: FnMut(&Self::Item), 

Call a closure on each element, passing the element on. The closure is called upon calls to advance or advance_back, and exactly once per element regardless of how many times (if any) get is called.

fn map<B, F>(self, f: F) -> Map<Self, B, F> where
    F: FnMut(&Self::Item) -> B, 

Creates an iterator which transforms elements of this iterator by passing them to a closure.

fn map_deref<B, F>(self, f: F) -> MapDeref<Self, F> where
    F: FnMut(&Self::Item) -> B, 

Creates a regular, non-streaming iterator which transforms elements of this iterator by passing them to a closure.

fn map_ref<B, F>(self, f: F) -> MapRef<Self, F> where
    F: Fn(&Self::Item) -> &B,
    B: ?Sized, 

Creates an iterator which transforms elements of this iterator by passing them to a closure.

fn nth(&mut self, n: usize) -> Option<&Self::Item>

Consumes the first n elements of the iterator, returning the next one.

fn position<F>(&mut self, f: F) -> Option<usize> where
    F: FnMut(&Self::Item) -> bool, 

Returns the index of the first element of the iterator matching a predicate.

fn skip(self, n: usize) -> Skip<Self>

Creates an iterator which skips the first n elements.

fn skip_while<F>(self, f: F) -> SkipWhile<Self, F> where
    F: FnMut(&Self::Item) -> bool, 

Creates an iterator that skips initial elements matching a predicate.

fn take(self, n: usize) -> Take<Self>

Creates an iterator which only returns the first n elements.

fn take_while<F>(self, f: F) -> TakeWhile<Self, F> where
    F: FnMut(&Self::Item) -> bool, 

Creates an iterator which only returns initial elements matching a predicate.

fn rev(self) -> Rev<Self> where
    Self: DoubleEndedStreamingIterator, 

Creates an iterator which returns elemens in the opposite order.

fn fold<B, F>(self, init: B, f: F) -> B where
    F: FnMut(B, &Self::Item) -> B, 

Reduces the iterator’s elements to a single, final value.

fn for_each<F>(self, f: F) where
    F: FnMut(&Self::Item), 

Calls a closure on each element of an iterator.