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

Field Summary

Fields

Modifier and Type	Field	Description
private static final GroupBy<?,?>	INSTANCE

Constructor Summary

Constructors

Modifier	Constructor	Description
private	GroupBy()

Method Summary

Modifier and Type	Method	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 Object

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

Methods inherited from interface Fn1

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

Methods inherited from interface Fn2

apply, apply, checkedApply, compose, contraMap, diMapL, discardR, flip, toBiFunction, uncurry, widen

Methods inherited from interface Functor

coerce

Field Details

INSTANCE

private static final GroupBy<?,?> INSTANCE

Constructor Details

GroupBy

private GroupBy()

Method Details

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)