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

public final class GroupBy<K,V>
extends java.lang.Object
implements Fn2<Fn1<? super V,? extends K>,java.lang.Iterable<V>,java.util.Map<K,java.util.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 GroupBy<?,?>	INSTANCE

Constructor Summary

Constructors

Modifier	Constructor	Description
private	GroupBy()

Method Summary

Modifier and Type	Method	Description
java.util.Map<K,java.util.List<V>>	checkedApply(Fn1<? super V,? extends K> keyFn, java.lang.Iterable<V> vs)
static <K,V> GroupBy<K,V>	groupBy()
static <K,V> Fn1<java.lang.Iterable<V>,java.util.Map<K,java.util.List<V>>>	groupBy(Fn1<? super V,? extends K> keyFn)
static <K,V> java.util.Map<K,java.util.List<V>>	groupBy(Fn1<? super V,? extends K> keyFn, java.lang.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.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 com.jnape.palatable.lambda.functions.Fn2

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

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

coerce

Field Detail

INSTANCE

private static final GroupBy<?,?> INSTANCE

Constructor Detail

GroupBy

private GroupBy()

Method Detail

checkedApply

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

Specified by:

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

groupBy

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

groupBy

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

groupBy

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