Trait differential_dataflow::operators::reduce::Count[−][src]

pub trait Count<G: Scope, K: Data, R: Semigroup> where
    G::Timestamp: Lattice + Ord, {
    fn count(&self) -> Collection<G, (K, R), isize>;
}

Extension trait for the count differential dataflow method.

Required methods

fn count(&self) -> Collection<G, (K, R), isize>[src]

Counts the number of occurrences of each element.

Examples

extern crate timely;
extern crate differential_dataflow;

use differential_dataflow::input::Input;
use differential_dataflow::operators::Count;

fn main() {
    ::timely::example(|scope| {
        // report the number of occurrences of each key
        scope.new_collection_from(1 .. 10).1
             .map(|x| x / 3)
             .count();
    });
}
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Implementors

impl<G: Scope, K: Data, T1, R: Semigroup> Count<G, K, R> for Arranged<G, T1> where
    G::Timestamp: Lattice + Ord,
    T1: TraceReader<Key = K, Val = (), Time = G::Timestamp, R = R> + Clone + 'static,
    T1::Batch: BatchReader<K, (), G::Timestamp, R>,
    T1::Cursor: Cursor<K, (), G::Timestamp, R>, [src]

impl<G: Scope, K: ExchangeData + Hashable, R: ExchangeData + Semigroup> Count<G, K, R> for Collection<G, K, R> where
    G::Timestamp: Lattice + Ord, [src]

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