Trait differential_dataflow::operators::group::Count [−][src]
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>,