edu.umd.cloud9.util.map
Class HMapKF<K extends Comparable<?>>

java.lang.Object
  edu.umd.cloud9.util.map.HMapKF<K>

Type Parameters:

K - the type of keys maintained by this map

All Implemented Interfaces:

MapKF<K>, Serializable, Cloneable

Direct Known Subclasses:

HMapKFW, HMapSFW

public class HMapKF<K extends Comparable<?>>
extends Object
implements MapKF<K>, Cloneable, Serializable

Hash-based implementation of the MapKF interface. MapKF is a specialized variant the standard Java Map interface, except that the values are hard coded as floats for efficiency reasons (keys can be arbitrary objects). This implementation was adapted from HashMap version 1.73, 03/13/07. See this benchmark for an efficiency comparison.

See Also:

Serialized Form

Constructor Summary

HMapKF()
Constructs an empty HMapKF with the default initial capacity (1024) and the default load factor (0.75).

HMapKF(int initialCapacity)
Constructs an empty HMapKF with the specified initial capacity and the default load factor (0.75).

HMapKF(int initialCapacity, float loadFactor)
Constructs an empty HMapKF with the specified initial capacity and load factor.

HMapKF(MapKF<? extends K> m)
Constructs a new HMapKF with the same mappings as the specified MapKF.

Method Summary

void	clear() Removes all of the mappings from this map.
Object	clone() Returns a shallow copy of this HMapKF instance: the keys and values themselves are not cloned.
boolean	containsKey(K key) Returns true if this map contains a mapping for the specified key.
boolean	containsValue(float value) Returns true if this map contains one or more mappings with the specified value.
float	dot(MapKF<K> m) Computes the dot product of this map with another map.
Set<MapKF.Entry<K>>	entrySet() Returns a Set view of the mappings contained in this map.
float	get(K key) Returns the value to which the specified key is mapped, or throws NoSuchElementException if this map contains no mapping for the key.
MapKF.Entry<K>[]	getEntriesSortedByValue() Returns entries sorted by descending value.
MapKF.Entry<K>[]	getEntriesSortedByValue(int n) Returns top n entries sorted by descending value.
boolean	isEmpty() Returns true if this map contains no key-value mappings.
Set<K>	keySet() Returns a Set view of the keys contained in this map.
float	length() Returns the length of the vector represented by this map.
void	normalize() Normalizes values such that the vector represented by this map has unit length.
void	plus(MapKF<K> m) Adds values of keys from another map to this map.
void	put(K key, float value) Associates the specified value with the specified key in this map.
void	putAll(MapKF<? extends K> m) Copies all of the mappings from the specified map to this map.
float	remove(K key) Removes the mapping for a key from this map if it is present.
int	size() Returns the number of key-value mappings in this map.
String	toString()
Collection<Float>	values() Returns a Collection view of the values contained in this map.

Methods inherited from class java.lang.Object

equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

Methods inherited from interface edu.umd.cloud9.util.map.MapKF

equals, hashCode

Constructor Detail

HMapKF

public HMapKF(int initialCapacity,
              float loadFactor)

Constructs an empty HMapKF with the specified initial capacity and load factor.

Parameters:

initialCapacity - the initial capacity

loadFactor - the load factor

Throws:

IllegalArgumentException - if the initial capacity is negative or the load factor is nonpositive

HMapKF

public HMapKF(int initialCapacity)

Constructs an empty HMapKF with the specified initial capacity and the default load factor (0.75).

Parameters:

initialCapacity - the initial capacity.

Throws:

IllegalArgumentException - if the initial capacity is negative.

HMapKF

public HMapKF()

Constructs an empty HMapKF with the default initial capacity (1024) and the default load factor (0.75).

HMapKF

public HMapKF(MapKF<? extends K> m)

Constructs a new HMapKF with the same mappings as the specified MapKF. The HMapKF is created with default load factor (0.75) and an initial capacity sufficient to hold the mappings in the specified MapKF.

Parameters:

m - the map whose mappings are to be placed in this map

Throws:

NullPointerException - if the specified map is null

Method Detail

size

public int size()

Description copied from interface: MapKF

Returns the number of key-value mappings in this map.

Specified by:

size in interface MapKF<K extends Comparable<?>>

Returns:

the number of key-value mappings in this map

isEmpty

public boolean isEmpty()

Description copied from interface: MapKF

Returns true if this map contains no key-value mappings.

Specified by:

isEmpty in interface MapKF<K extends Comparable<?>>

Returns:

true if this map contains no key-value mappings

get

public float get(K key)

Description copied from interface: MapKF

Returns the value to which the specified key is mapped, or throws NoSuchElementException if this map contains no mapping for the key.

Specified by:

get in interface MapKF<K extends Comparable<?>>

Parameters:

key - the key whose associated value is to be returned

Returns:

the value to which the specified key is mapped

containsKey

public boolean containsKey(K key)

Description copied from interface: MapKF

Returns true if this map contains a mapping for the specified key.

Specified by:

containsKey in interface MapKF<K extends Comparable<?>>

Parameters:

key - key whose presence in this map is to be tested

Returns:

true if this map contains a mapping for the specified key

put

public void put(K key,
                float value)

Description copied from interface: MapKF

Associates the specified value with the specified key in this map. If the map previously contained a mapping for the key, the old value is replaced by the specified value.

Specified by:

put in interface MapKF<K extends Comparable<?>>

Parameters:

key - key with which the specified value is to be associated

value - value to be associated with the specified key

putAll

public void putAll(MapKF<? extends K> m)

Description copied from interface: MapKF

Copies all of the mappings from the specified map to this map.

Specified by:

putAll in interface MapKF<K extends Comparable<?>>

Parameters:

m - mappings to be stored in this map

remove

public float remove(K key)

Description copied from interface: MapKF

Removes the mapping for a key from this map if it is present. No action is performed if this map does not contain the key.

Specified by:

remove in interface MapKF<K extends Comparable<?>>

Parameters:

key - key whose mapping is to be removed from the map

clear

public void clear()

Description copied from interface: MapKF

Removes all of the mappings from this map. The map will be empty after this call returns.

Specified by:

clear in interface MapKF<K extends Comparable<?>>

containsValue

public boolean containsValue(float value)

Description copied from interface: MapKF

Returns true if this map contains one or more mappings with the specified value.

Specified by:

containsValue in interface MapKF<K extends Comparable<?>>

Parameters:

value - value whose presence in this map is to be tested

Returns:

true this map contains one or more mappings with the specified value

clone

public Object clone()

Returns a shallow copy of this HMapKF instance: the keys and values themselves are not cloned.

Overrides:

clone in class Object

Returns:

a shallow copy of this map

keySet

public Set<K> keySet()

Description copied from interface: MapKF

Returns a Set view of the keys contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. See Map.keySet() for more details.

Specified by:

keySet in interface MapKF<K extends Comparable<?>>

Returns:

a set view of the keys contained in this map

values

public Collection<Float> values()

Description copied from interface: MapKF

Returns a Collection view of the values contained in this map. Note that this is a inefficient operation since it triggers autoboxing of the float values, which is exactly what this implementation is trying to avoid. Unlike a standard Java Map, values in the backing map cannot be altered with this collection view.

Specified by:

values in interface MapKF<K extends Comparable<?>>

Returns:

a collection view of the values contained in this map

entrySet

public Set<MapKF.Entry<K>> entrySet()

Description copied from interface: MapKF

Returns a Set view of the mappings contained in this map. The set is backed by the map, so changes to the map are reflected in the set, and vice-versa. See Map.entrySet() for more details.

Specified by:

entrySet in interface MapKF<K extends Comparable<?>>

Returns:

a set view of the mappings contained in this map

toString

public String toString()

Overrides:

toString in class Object

plus

public void plus(MapKF<K> m)

Adds values of keys from another map to this map.

Parameters:

m - the other map

dot

public float dot(MapKF<K> m)

Computes the dot product of this map with another map.

Parameters:

m - the other map

length

public float length()

Returns the length of the vector represented by this map.

Returns:

length of the vector represented by this map

normalize

public void normalize()

Normalizes values such that the vector represented by this map has unit length.

getEntriesSortedByValue

public MapKF.Entry<K>[] getEntriesSortedByValue()

Returns entries sorted by descending value. Ties broken by the key.

Returns:

entries sorted by descending value

getEntriesSortedByValue

public MapKF.Entry<K>[] getEntriesSortedByValue(int n)

Returns top n entries sorted by descending value. Ties broken by the key.

Parameters:

n - number of entries to return

Returns:

top n entries sorted by descending value