Trait Threshold

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

    // Provided methods
    fn threshold<R2: Ord + Abelian + 'static, F: FnMut(&K, &R1) -> R2 + 'static>(
        &self,
        thresh: F,
    ) -> Collection<G, K, R2> { ... }
    fn distinct(&self) -> Collection<G, K, isize> { ... }
    fn distinct_core<R2: Ord + Abelian + 'static + From<i8>>(
        &self,
    ) -> Collection<G, K, R2> { ... }
}

Extension trait for the threshold and distinct differential dataflow methods.

Required Methods

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

A threshold with the ability to name the operator.

Provided Methods

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

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

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

::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>

Reduces the collection to one occurrence of each distinct element.

Examples

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

::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: Ord + Abelian + 'static + From<i8>>( &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.

Dyn Compatibility

This trait is not dyn compatible.

In older versions of Rust, dyn compatibility was called "object safety", so this trait is not object safe.

Implementors

impl<G, K: Data, T1, R1: Semigroup> Threshold<G, K, R1> for Arranged<G, T1>

where G: Scope<Timestamp = T1::Time>, T1: for<'a> TraceReader<Key<'a> = &'a K, Val<'a> = &'a (), Diff = R1> + Clone + 'static, for<'a> T1::Key<'a>: IntoOwned<'a, Owned = K>,

impl<G: Scope, K: ExchangeData + Hashable, R1: ExchangeData + Semigroup> Threshold<G, K, R1> for Collection<G, K, R1>

where G::Timestamp: Lattice + Ord,