it.unimi.dsi.fastutil.doubles
Class Double2ObjectOpenHashMap

java.lang.Object
  extended byit.unimi.dsi.fastutil.doubles.AbstractDouble2ObjectMap
      extended byit.unimi.dsi.fastutil.doubles.Double2ObjectOpenHashMap
All Implemented Interfaces:
Cloneable, Double2ObjectMap, Hash, Map, Serializable

public class Double2ObjectOpenHashMap
extends AbstractDouble2ObjectMap
implements Serializable, Cloneable, Hash, Double2ObjectMap

A type-specific hash map with a fast, small-footprint implementation.

Instances of this class use a hash table to represent a map. The table is enlarged as needed when new entries are created, but it is never made smaller (even on a clear()). A family of trimming methods lets you control the size of the table; this is particularly useful if you reuse instances of this class.

The enlargement speed is controlled by the growth factor, a positive number. If the growth factor is p, then the table is enlarged each time roughly by a factor 2p/16. By default, p is Hash.DEFAULT_GROWTH_FACTOR, which means that the table is doubled at each enlargement, but one can easily set more or less aggressive policies by calling growthFactor(int) (note that the growth factor is not serialised: deserialised tables gets the default growth factor).

See Also:
Hash, HashCommon, Serialized Form

Field Summary
static long serialVersionUID
           
 
Fields inherited from interface it.unimi.dsi.fastutil.Hash
DEFAULT_GROWTH_FACTOR, DEFAULT_INITIAL_SIZE, DEFAULT_LOAD_FACTOR, FREE, OCCUPIED, PRIMES, REMOVED
 
Constructor Summary
Double2ObjectOpenHashMap()
          Creates a new hash map with Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.
Double2ObjectOpenHashMap(Double2ObjectMap m)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one.
Double2ObjectOpenHashMap(Double2ObjectMap m, float f)
          Creates a new hash map copying a given type-specific one.
Double2ObjectOpenHashMap(int n)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.
Double2ObjectOpenHashMap(int n, float f)
          Creates a new hash map.
Double2ObjectOpenHashMap(Map m)
          Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one.
Double2ObjectOpenHashMap(Map m, float f)
          Creates a new hash map copying a given one.
 
Method Summary
 void clear()
           
 Object clone()
          Returns a deep copy of this map.
 boolean containsKey(double k)
           
 boolean containsValue(Object v)
           
 Set entrySet()
           
 Object get(double k)
          Returns the value to which the given key is mapped.
 Object get(Object ok)
           
 int growthFactor()
          Gets the growth factor.
 void growthFactor(int growthFactor)
          Sets the growth factor.
 int hashCode()
          Returns a hash code for this map.
 boolean isEmpty()
           
 Set keySet()
           
 Object put(double k, Object v)
          Adds a pair to the map.
 Object put(Object ok, Object ov)
           
 boolean rehash()
          Rehashes this map without changing the table size.
 Object remove(double k)
          Removes the mapping with the given key.
 Object remove(Object ok)
           
 int size()
           
 boolean trim()
          Rehashes the map, making the table as small as possible.
 boolean trim(int n)
          Rehashes this map if the table is too large.
 Collection values()
           
 
Methods inherited from class it.unimi.dsi.fastutil.doubles.AbstractDouble2ObjectMap
containsKey, defaultReturnValue, defaultReturnValue, equals, getDefRetValue, putAll, setDefRetValue, toString
 
Methods inherited from class java.lang.Object
getClass, notify, notifyAll, wait, wait, wait
 
Methods inherited from interface it.unimi.dsi.fastutil.doubles.Double2ObjectMap
defaultReturnValue, defaultReturnValue, getDefRetValue, setDefRetValue
 
Methods inherited from interface java.util.Map
containsKey, equals, putAll
 

Field Detail

serialVersionUID

public static final long serialVersionUID
See Also:
Constant Field Values
Constructor Detail

Double2ObjectOpenHashMap

public Double2ObjectOpenHashMap(int n,
                                float f)
Creates a new hash map. The actual table size is the least available prime greater than n/f.

Parameters:
n - the expected number of elements in the hash map.
f - the load factor.
See Also:
Hash.PRIMES

Double2ObjectOpenHashMap

public Double2ObjectOpenHashMap(int n)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor.

Parameters:
n - the expected number of elements in the hash map.

Double2ObjectOpenHashMap

public Double2ObjectOpenHashMap()
Creates a new hash map with Hash.DEFAULT_INITIAL_SIZE entries and Hash.DEFAULT_LOAD_FACTOR as load factor.


Double2ObjectOpenHashMap

public Double2ObjectOpenHashMap(Map m,
                                float f)
Creates a new hash map copying a given one.

Parameters:
m - a Map to be copied into the new hash map.
f - the load factor.

Double2ObjectOpenHashMap

public Double2ObjectOpenHashMap(Map m)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given one.

Parameters:
m - a Map to be copied into the new hash map.

Double2ObjectOpenHashMap

public Double2ObjectOpenHashMap(Double2ObjectMap m,
                                float f)
Creates a new hash map copying a given type-specific one.

Parameters:
m - a type-specific map to be copied into the new hash map.
f - the load factor.

Double2ObjectOpenHashMap

public Double2ObjectOpenHashMap(Double2ObjectMap m)
Creates a new hash map with Hash.DEFAULT_LOAD_FACTOR as load factor copying a given type-specific one.

Parameters:
m - a type-specific map to be copied into the new hash map.
Method Detail

growthFactor

public void growthFactor(int growthFactor)
Sets the growth factor. Subsequent enlargements will increase the table size roughly by a multiplicative factor of 2p/16.

Parameters:
growthFactor - the new growth factor; it must be positive.

growthFactor

public int growthFactor()
Gets the growth factor.

Returns:
the growth factor of this set.

put

public Object put(Object ok,
                  Object ov)
Specified by:
put in interface Map

put

public Object put(double k,
                  Object v)
Description copied from interface: Double2ObjectMap
Adds a pair to the map.

Specified by:
put in interface Double2ObjectMap
Parameters:
k - the key.
v - the value.
Returns:
the old value, or the default return value if no value was present for the given key.
See Also:
Map.put(Object,Object)

remove

public Object remove(Object ok)
Specified by:
remove in interface Map

containsValue

public boolean containsValue(Object v)
Specified by:
containsValue in interface Map

clear

public void clear()
Specified by:
clear in interface Map

containsKey

public boolean containsKey(double k)
Specified by:
containsKey in interface Double2ObjectMap
See Also:
Map.containsKey(Object)

size

public int size()
Specified by:
size in interface Map

isEmpty

public boolean isEmpty()
Specified by:
isEmpty in interface Map

get

public Object get(Object ok)
Specified by:
get in interface Map

get

public Object get(double k)
Description copied from interface: Double2ObjectMap
Returns the value to which the given key is mapped.

Specified by:
get in interface Double2ObjectMap
Parameters:
k - the key.
Returns:
the corresponding value, or the default return value if no value was present for the given key.
See Also:
Map.get(Object)

remove

public Object remove(double k)
Description copied from interface: Double2ObjectMap
Removes the mapping with the given key.

Specified by:
remove in interface Double2ObjectMap
Parameters:
k -
Returns:
the old value, or the default return value if no value was present for the given key.
See Also:
Map.remove(Object)

entrySet

public Set entrySet()
Specified by:
entrySet in interface Map

keySet

public Set keySet()
Specified by:
keySet in interface Map

values

public Collection values()
Specified by:
values in interface Map

rehash

public boolean rehash()
Rehashes this map without changing the table size.

This method should be called when the map underwent numerous deletions and insertions. In this case, free entries become rare, and unsuccessful searches require probing all entries. For reasonable load factors this method is linear in the number of entries. You will need as much additional free memory as that occupied by the table.

If you need to reduce the table siza to fit exactly this map, you must use trim().

Returns:
true if there was enough memory to rehash the map, false otherwise.
See Also:
trim()

trim

public boolean trim()
Rehashes the map, making the table as small as possible.

This method rehashes to the smallest size satisfying the load factor. It can be used when the map will not be changed anymore, so to optimise access speed (by collecting deleted entries) and size.

If the table size is already the minimum possible, this method does nothing. If you want to guarantee rehashing, use rehash().

Returns:
true if there was enough memory to trim the map.
See Also:
trim(int), rehash()

trim

public boolean trim(int n)
Rehashes this map if the table is too large.

Let N be the smallest table size that can hold n entries, still satisfying the load factor. If the current table size is smaller than or equal to N, or if the number of elements of this map is larger than n, this method does nothing. Otherwise, it rehashes this map in a table of size N.

This method is useful when reusing maps. Clearing a map leaves the table size untouched. If you are reusing a map many times, you can call this method with a typical size to avoid keeping around a very large table just because of a few large transient maps.

Parameters:
n - the threshold for the trimming.
Returns:
true if there was enough memory to trim the map.
See Also:
trim(), rehash()

clone

public Object clone()
Returns a deep copy of this map.

This method performs a deep copy of this hash map; the data stored in the map, however, is not cloned. Note that this makes a difference only for object keys.

Returns:
a deep copy of this map.

hashCode

public int hashCode()
Returns a hash code for this map. This method overrides the generic method provided by the superclass. Since equals() is not overriden, it is important that the value returned by this method is the same value as the one returned by the overriden method.

Specified by:
hashCode in interface Map
Overrides:
hashCode in class AbstractDouble2ObjectMap
Returns:
a hash code for this map.