net.sf.tweety.commons.util

Class MapTools<E,F>

java.lang.Object

net.sf.tweety.commons.util.MapTools<E,F>

Type Parameters:

E - Domain class of the maps

F - Range class of the maps

public class MapTools<E,F>
extends Object

This class provides some utility functions for maps.

Author:

Matthias Thimm

Constructor Summary

Constructors

Constructor and Description
MapTools()

Method Summary

Modifier and Type	Method and Description
Set<Map<E,F>>	allBijections(Collection<E> domain, Collection<F> range) Computes all bijections from E to F.
Set<Map<E,F>>	allMaps(Map<Set<E>,Set<F>> relations) Computes the complete set of maps from E to F such that the following condition holds.
Set<Map<E,F>>	allMaps(Set<? extends E> domain, Set<? extends F> range) This methods computes all maps from domain to range.
Set<Map<E,F>>	allMapsSingleSource(Map<E,Set<F>> relations) Computes the complete set of maps from E to F such that the following condition holds.
Map<E,F>	combine(Set<Map<E,F>> singleMaps) Combines all maps in singleMaps to one maps containing every assignment of each map in singleMaps.
static boolean	isInjective(Map<? extends Object,? extends Object> map) Checks whether the given map is injective, i.e.

Methods inherited from class java.lang.Object

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

Constructor Detail

MapTools

public MapTools()

Method Detail

allMaps

public Set<Map<E,F>> allMaps(Map<Set<E>,Set<F>> relations)

Computes the complete set of maps from E to F such that the following condition holds. For every map "m" in the result the set m.keySet() is equal to the union of all sets S with S in relations.keySet() and each element "e" in m.keySet() is mapped to an element "f" such that "f" in relations.get(S) with "e" in S. For example the map:
{a,b} => {1,2}
{c,d} => {3}
{f} => {4,5}
yields the set of maps:
a=>1, b=>1, c=>3, d=>3, f=>4
a=>1, b=>1, c=>3, d=>3, f=>5
a=>1, b=>2, c=>3, d=>3, f=>4
a=>1, b=>2, c=>3, d=>3, f=>5
a=>2, b=>1, c=>3, d=>3, f=>4
a=>2, b=>1, c=>3, d=>3, f=>5
a=>2, b=>2, c=>3, d=>3, f=>4
a=>2, b=>2, c=>3, d=>3, f=>5

Parameters:

relations - a map from sets of E to sets of F.

Returns:

a set of maps from E to F.

allMapsSingleSource

public Set<Map<E,F>> allMapsSingleSource(Map<E,Set<F>> relations)

Computes the complete set of maps from E to F such that the following condition holds. For every map "m" in the result the set m.keySet() is equal to relations.keySet() and each element "e" in m.keySet() is mapped to an element "f" such that "f" in relations.get(S) with "e" in S. For example the map:
a => {1,2}
b => {3}
c => {4,5}
yields the set of maps:
a=>1, b=>3, c=>4
a=>1, b=>3, c=>5
a=>2, b=>3, c=>4
a=>2, b=>3, c=>5

Parameters:

relations - a map from sets of E to sets of F.

Returns:

a set of maps from E to F.

allBijections

public Set<Map<E,F>> allBijections(Collection<E> domain,
                                   Collection<F> range)

Computes all bijections from E to F. E and F have to be of the same cardinality.

Parameters:

domain - some set.

range - some set.

Returns:

all bijections from E to F.

allMaps

public Set<Map<E,F>> allMaps(Set<? extends E> domain,
                             Set<? extends F> range)

This methods computes all maps from domain to range.

Parameters:

domain - a set of elements.

range - a set of elements

Returns:

a set of maps, where every map maps any element of domain to an element of range.

combine

public Map<E,F> combine(Set<Map<E,F>> singleMaps)
                 throws IllegalArgumentException

Combines all maps in singleMaps to one maps containing every assignment of each map in singleMaps.

Parameters:

singleMaps - the set of maps to be combined.

Returns:

a single map.

Throws:

IllegalArgumentException - if one key is used in more than one map of singleMaps.

isInjective

public static boolean isInjective(Map<? extends Object,? extends Object> map)

Checks whether the given map is injective, i.e. whether no two different keys are assigned the same value.

Parameters:

map - a map

Returns:

"true" iff the given map is injective.