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

pub trait Threshold<G: Scope, K: Data, R1: Semigroup> where
    G::Timestamp: Lattice + Ord, {
    fn threshold_named<R2: Abelian, F: FnMut(&K, &R1) -> R2 + 'static>(
        &self, 
        name: &str, 
        thresh: F
    ) -> Collection<G, K, R2>;

    fn threshold<R2: Abelian, F: FnMut(&K, &R1) -> R2 + 'static>(
        &self, 
        thresh: F
    ) -> Collection<G, K, R2> { ... }

    fn distinct(&self) -> Collection<G, K, isize> { ... }

    fn distinct_core<R2: Abelian + From<i8>>(&self) -> Collection<G, K, R2> { ... }
}

Extension trait for the threshold and distinct differential dataflow methods.

Required methods

fn threshold_named<R2: Abelian, F: FnMut(&K, &R1) -> R2 + 'static>(
    &self,
    name: &str,
    thresh: F
) -> Collection<G, K, R2>[src]

A threshold with the ability to name the operator.

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Provided methods

fn threshold<R2: Abelian, F: FnMut(&K, &R1) -> R2 + 'static>(
    &self,
    thresh: F
) -> Collection<G, K, R2>[src]

Transforms the multiplicity of records.

The threshold function is obliged to map R1::zero to R2::zero, or at least the computation may behave as if it does. Otherwise, the transformation can be nearly arbitrary: the code does not assume any properties of threshold.

Examples

extern crate timely;
extern crate differential_dataflow;

use differential_dataflow::input::Input;
use differential_dataflow::operators::Threshold;

fn main() {
    ::timely::example(|scope| {
        // report at most one of each key.
        scope.new_collection_from(1 .. 10).1
             .map(|x| x / 3)
             .threshold(|_,c| c % 2);
    });
}

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

Reduces the collection to one occurrence of each distinct element.

Examples

extern crate timely;
extern crate differential_dataflow;

use differential_dataflow::input::Input;
use differential_dataflow::operators::Threshold;

fn main() {
    ::timely::example(|scope| {
        // report at most one of each key.
        scope.new_collection_from(1 .. 10).1
             .map(|x| x / 3)
             .distinct();
    });
}

fn distinct_core<R2: Abelian + From<i8>>(&self) -> Collection<G, K, R2>[src]

Distinct for general integer differences.

This method allows distinct to produce collections whose difference type is something other than an isize integer, for example perhaps an i32.

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Implementors

impl<G: Scope, K: Data, T1, R1: Semigroup> Threshold<G, K, R1> for Arranged<G, T1> where
    G::Timestamp: Lattice + Ord,
    T1: TraceReader<Key = K, Val = (), Time = G::Timestamp, R = R1> + Clone + 'static,
    T1::Batch: BatchReader<K, (), G::Timestamp, R1>,
    T1::Cursor: Cursor<K, (), G::Timestamp, R1>, [src]

impl<G: Scope, K: ExchangeData + Hashable, R1: ExchangeData + Semigroup> Threshold<G, K, R1> for Collection<G, K, R1> where
    G::Timestamp: Lattice + Ord, [src]

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