Trait differential_dataflow::operators::threshold::ThresholdTotal

pub trait ThresholdTotal<G: Scope, K: ExchangeData, R: ExchangeData + Semigroup>
where
    G::Timestamp: TotalOrder + Lattice + Ord,
{
    // Required method
    fn threshold_semigroup<R2, F>(&self, thresh: F) -> Collection<G, K, R2>
       where R2: Semigroup + 'static,
             F: FnMut(&K, &R, Option<&R>) -> Option<R2> + 'static;

    // Provided methods
    fn threshold_total<R2: Abelian + 'static, F: FnMut(&K, &R) -> R2 + 'static>(
        &self,
        thresh: F,
    ) -> Collection<G, K, R2> { ... }
    fn distinct_total(&self) -> Collection<G, K, isize> { ... }
    fn distinct_total_core<R2: Abelian + From<i8> + 'static>(
        &self,
    ) -> Collection<G, K, R2> { ... }
}

Extension trait for the distinct differential dataflow method.

Required Methods

fn threshold_semigroup<R2, F>(&self, thresh: F) -> Collection<G, K, R2>

where R2: Semigroup + 'static, F: FnMut(&K, &R, Option<&R>) -> Option<R2> + 'static,

Reduces the collection to one occurrence of each distinct element.

Provided Methods

fn threshold_total<R2: Abelian + 'static, F: FnMut(&K, &R) -> R2 + 'static>( &self, thresh: F, ) -> Collection<G, K, R2>

Reduces the collection to one occurrence of each distinct element.

Examples

use differential_dataflow::input::Input;
use differential_dataflow::operators::ThresholdTotal;

::timely::example(|scope| {
    // report the number of occurrences of each key
    scope.new_collection_from(1 .. 10).1
         .map(|x| x / 3)
         .threshold_total(|_,c| c % 2);
});

fn distinct_total(&self) -> Collection<G, K, isize>

Reduces the collection to one occurrence of each distinct element.

This reduction only tests whether the weight associated with a record is non-zero, and otherwise ignores its specific value. To take more general actions based on the accumulated weight, consider the threshold method.

Examples

use differential_dataflow::input::Input;
use differential_dataflow::operators::ThresholdTotal;

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

fn distinct_total_core<R2: Abelian + From<i8> + 'static>( &self, ) -> Collection<G, K, R2>

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.

Object Safety

This trait is not object safe.

Implementors

impl<G, K, T1> ThresholdTotal<G, K, <T1 as TraceReader>::Diff> for Arranged<G, T1>

where G: Scope<Timestamp = T1::Time>, T1: for<'a> TraceReader<Key<'a> = &'a K, Val<'a> = &'a ()> + Clone + 'static, for<'a> T1::Diff: Semigroup<T1::DiffGat<'a>> + ExchangeData, K: ExchangeData, T1::Time: TotalOrder,

impl<G: Scope, K: ExchangeData + Hashable, R: ExchangeData + Semigroup> ThresholdTotal<G, K, R> for Collection<G, K, R>

where G::Timestamp: TotalOrder + Lattice + Ord,