fn limit<G, K, V>(input: &Collection<G,(K,V)>, limit: usize) -> Collection<G,Vec<K>> 
where
    G: Scope,
    G::Timestamp: Lattice,
    K: ExchangeData+std::hash::Hash,
    V: ExchangeData,
{
    use differential_dataflow::hashable::Hashable;
    use differential_dataflow::operators::reduce::Reduce;

    let input = input.map(|(key,val)| (key.hashed(),(val,key)));

    let top_k =
    input
        .map(|(hash,(val,key))| (hash % 10000, (val,key)))
        .reduce(move |_key, input, output| {
            for ((val, key), _wgt) in input.iter().rev().take(limit) {
                output.push(((val.clone(), key.clone()), 1));
            }
        })
        .map(|(hash, (val,key))| (hash % 100, (val,key)))
        .reduce(move |_key, input, output| {
            for ((val, key), _wgt) in input.iter().rev().take(limit) {
                output.push(((val.clone(), key.clone()), 1));
            }
        })
        .map(|(hash, (val,key))| (hash % 1, (val,key)));

    top_k
        .reduce(move |_zero, input, output| {
            let mut result = Vec::new();
            result.extend(input.iter().rev().take(limit).map(|((_val,key),_wgt)| key.clone()));
            output.push((result, 1));
        })
        .map(|(_hash,vec)| vec)
}
/// Return the top `limit` distinct keys in input, by value.
Return the top `limit` distinct keys in input, by value.
Return the top ` limit ` distinct keys in input by value .
fn limit<G, K, V>(input: &Collection<G,(K,V)>, limit: usize) -> Collection<G,Vec<K>> 
where
    G: Scope,
    G::Timestamp: Lattice,
    K: ExchangeData+std::hash::Hash,
    V: ExchangeData,
{
    use differential_dataflow::hashable::Hashable;
    use differential_dataflow::operators::reduce::Reduce;
    let input = input.map(|(key,val)| (key.hashed(),(val,key)));
    let top_k =
    input
        .map(|(hash,(val,key))| (hash % 10000, (val,key)))
        .reduce(move |_key, input, output| {
            for ((val, key), _wgt) in input.iter().rev().take(limit) {
                output.push(((val.clone(), key.clone()), 1));
            }
        })
        .map(|(hash, (val,key))| (hash % 100, (val,key)))
        .reduce(move |_key, input, output| {
            for ((val, key), _wgt) in input.iter().rev().take(limit) {
                output.push(((val.clone(), key.clone()), 1));
            }
        })
        .map(|(hash, (val,key))| (hash % 1, (val,key)));
    top_k
        .reduce(move |_zero, input, output| {
            let mut result = Vec::new();
            result.extend(input.iter().rev().take(limit).map(|((_val,key),_wgt)| key.clone()));
            output.push((result, 1));
        })
        .map(|(_hash,vec)| vec)
}
fn limit < G , K , V > ( input : & Collection < G , ( K , V ) > , limit : usize ) -> Collection < G , Vec < K > > where G : Scope , G :: Timestamp : Lattice , K : ExchangeData + std :: hash :: Hash , V : ExchangeData , { use differential_dataflow :: hashable :: Hashable ; use differential_dataflow :: operators :: reduce :: Reduce ; let input = input . map ( | ( key , val ) | ( key . hashed ( ) , ( val , key ) ) ) ; let top_k = input . map ( | ( hash , ( val , key ) ) | ( hash % 10000 , ( val , key ) ) ) . reduce ( move | _key , input , output | { for ( ( val , key ) , _wgt ) in input . iter ( ) . rev ( ) . take ( limit ) { output . push ( ( ( val . clone ( ) , key . clone ( ) ) , 1 ) ) ; } } ) . map ( | ( hash , ( val , key ) ) | ( hash % 100 , ( val , key ) ) ) . reduce ( move | _key , input , output | { for ( ( val , key ) , _wgt ) in input . iter ( ) . rev ( ) . take ( limit ) { output . push ( ( ( val . clone ( ) , key . clone ( ) ) , 1 ) ) ; } } ) . map ( | ( hash , ( val , key ) ) | ( hash % 1 , ( val , key ) ) ) ; top_k . reduce ( move | _zero , input , output | { let mut result = Vec :: new ( ) ; result . extend ( input . iter ( ) . rev ( ) . take ( limit ) . map ( | ( ( _val , key ) , _wgt ) | key . clone ( ) ) ) ; output . push ( ( result , 1 ) ) ; } ) . map ( | ( _hash , vec ) | vec ) }
Return the top `limit` distinct keys in input, by value.
Return the top ` limit ` distinct keys in input by value .
input
&Collection<G,(K,V)>
limit
usize
input
&Collection<G,(K,V)>
limit
usize