com.jnape.palatable.lambda.functions.builtin.fn2

Class GroupBy<K,V>

java.lang.Object

com.jnape.palatable.lambda.functions.builtin.fn2.GroupBy<K,V>

Type Parameters:

K - the Map key type

V - the Map value type

All Implemented Interfaces:

Fn1<Fn1<? super V,? extends K>,Fn1<Iterable<V>,Map<K,List<V>>>>, Fn2<Fn1<? super V,? extends K>,Iterable<V>,Map<K,List<V>>>, Applicative<Fn1<Iterable<V>,Map<K,List<V>>>,Fn1<Fn1<? super V,? extends K>,?>>, Cartesian<Fn1<? super V,? extends K>,Fn1<Iterable<V>,Map<K,List<V>>>,Fn1<?,?>>, Cocartesian<Fn1<? super V,? extends K>,Fn1<Iterable<V>,Map<K,List<V>>>,Fn1<?,?>>, Contravariant<Fn1<? super V,? extends K>,Profunctor<?,Fn1<Iterable<V>,Map<K,List<V>>>,Fn1<?,?>>>, Functor<Fn1<Iterable<V>,Map<K,List<V>>>,Fn1<Fn1<? super V,? extends K>,?>>, Profunctor<Fn1<? super V,? extends K>,Fn1<Iterable<V>,Map<K,List<V>>>,Fn1<?,?>>, Monad<Fn1<Iterable<V>,Map<K,List<V>>>,Fn1<Fn1<? super V,? extends K>,?>>, MonadReader<Fn1<? super V,? extends K>,Fn1<Iterable<V>,Map<K,List<V>>>,Fn1<Fn1<? super V,? extends K>,?>>, MonadRec<Fn1<Iterable<V>,Map<K,List<V>>>,Fn1<Fn1<? super V,? extends K>,?>>, MonadWriter<Fn1<? super V,? extends K>,Fn1<Iterable<V>,Map<K,List<V>>>,Fn1<Fn1<? super V,? extends K>,?>>

public final class GroupBy<K,V>
extends Object
implements Fn2<Fn1<? super V,? extends K>,Iterable<V>,Map<K,List<V>>>

Given an Iterable<V> vs and a key function V -> K f, fold vs into a Map<K, List<V>> by applying f to each element of vs, retaining values that map to the same key in a list, in the order they were iterated in.

See Also:

InGroupsOf

Method Summary

Modifier and Type	Method and Description
Map<K,List<V>>	checkedApply(Fn1<? super V,? extends K> keyFn, Iterable<V> vs)
static <K,V> GroupBy<K,V>	groupBy()
static <K,V> Fn1<Iterable<V>,Map<K,List<V>>>	groupBy(Fn1<? super V,? extends K> keyFn)
static <K,V> Map<K,List<V>>	groupBy(Fn1<? super V,? extends K> keyFn, Iterable<V> vs)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface com.jnape.palatable.lambda.functions.Fn2

apply, apply, checkedApply, compose, contraMap, curried, curry, diMapL, discardR, flip, fn2, fromBiFunction, toBiFunction, uncurry, widen

Methods inherited from interface com.jnape.palatable.lambda.functions.Fn1

andThen, carry, cartesian, censor, choose, cocartesian, diMap, diMapR, discardL, flatMap, fmap, fn1, fromFunction, lazyZip, listens, local, pure, pureFn1, thunk, toFunction, trampolineM, zip, zip

Methods inherited from interface com.jnape.palatable.lambda.monad.Monad

join

Methods inherited from interface com.jnape.palatable.lambda.functor.Functor

coerce

Method Detail

checkedApply

public Map<K,List<V>> checkedApply(Fn1<? super V,? extends K> keyFn,
                                   Iterable<V> vs)

Specified by:

checkedApply in interface Fn2<Fn1<? super V,? extends K>,Iterable<V>,Map<K,List<V>>>

groupBy

public static <K,V> GroupBy<K,V> groupBy()

groupBy

public static <K,V> Fn1<Iterable<V>,Map<K,List<V>>> groupBy(Fn1<? super V,? extends K> keyFn)

groupBy

public static <K,V> Map<K,List<V>> groupBy(Fn1<? super V,? extends K> keyFn,
                                           Iterable<V> vs)