Trait differential_dataflow::operators::group::Count

pub trait Count<G: Scope, K: Data, R: Diff>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>

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();
    });
}

Implementors

impl<G: Scope, K: Data + Hashable, R: Diff> Count<G, K, R> for Collection<G, K, R>where
    G::Timestamp: Lattice + Ord,

impl<G: Scope, K: Data, T1, R: Diff> Count<G, K, R> for Arranged<G, K, (), R, T1>where
    G::Timestamp: Lattice + Ord,
    T1: TraceReader<K, (), G::Timestamp, R> + Clone + 'static,
    T1::Batch: BatchReader<K, (), G::Timestamp, R>,