de.torstennahm.integrate.sparse.index
Class FastIndex

java.lang.Object
  de.torstennahm.integrate.sparse.index.FastIndex

All Implemented Interfaces:

Index, java.lang.Iterable<de.torstennahm.math.IntEntry>

public class FastIndex
extends java.lang.Object
implements Index

Implements Index. Only the non-zero entries for the index are stored. For performance, an array is used for storage, which is grown when needed.

According to general index contract, this class is thread-safe.

Author:

Torsten Nahm

Field Summary

protected int[]	entryNums Array storing the entry number of each entry.
protected int[]	entryVals Array storing the corresponding value of each entry.
protected int	hashCode Hash code.
protected int	nonZeroEntries Number of entries that are not zero.

Constructor Summary

FastIndex()
Creates a new fast index.

FastIndex(Index index)
Creates an new FastIndex from any Index.

FastIndex(int[] array)
Creates a fast index from an array.

FastIndex(de.torstennahm.math.SparseIntVector vector)
Creates a new FastIndex from a PackedIntVector.

Method Summary

Index	add(int entryNum, int add) Returns a new index with the specified increment at the specified entry.
boolean	equals(java.lang.Object o) Compares the specified object with this index for equality.
int	get(int entryNum) Returns the value for the specified entry.
int	hashCode() Returns the hash code value for this index.
java.util.Iterator<de.torstennahm.math.IntEntry>	iterator() Returns an IntPairIterator for iterating over the index.
int	lastEntry() Returns the index of highest entry whose value is not 0.
protected static int	newHash(int hashCode, int entryNum, int oldVal, int newVal)
int	nonZeroEntries() Returns the number of entries with values not equal to 0.
Index	set(int entryNum, int value) Returns a new index with the specified new value at the specified entry.
int	sum() Returns the the sum of all entry values.
java.lang.String	toString()

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Field Detail

nonZeroEntries

protected int nonZeroEntries

Number of entries that are not zero.

entryNums

protected int[] entryNums

Array storing the entry number of each entry.

entryVals

protected int[] entryVals

Array storing the corresponding value of each entry.

hashCode

protected int hashCode

Hash code.

Constructor Detail

FastIndex

public FastIndex()

Creates a new fast index. All entries are initially zero.

FastIndex

public FastIndex(Index index)

Creates an new FastIndex from any Index.

Parameters:

index - index to initialize from

FastIndex

public FastIndex(de.torstennahm.math.SparseIntVector vector)

Creates a new FastIndex from a PackedIntVector.

Parameters:

vector - vector to initialize from

FastIndex

public FastIndex(int[] array)

Creates a fast index from an array.

Parameters:

array - array to initialize from

Method Detail

nonZeroEntries

public int nonZeroEntries()

Description copied from interface: Index

Returns the number of entries with values not equal to 0.

Specified by:

nonZeroEntries in interface Index

Returns:

number of entries with value != 0

lastEntry

public int lastEntry()

Description copied from interface: Index

Returns the index of highest entry whose value is not 0.

Specified by:

lastEntry in interface Index

Returns:

number of last non-0 entry, -1 if all entries are 0

get

public int get(int entryNum)

Description copied from interface: Index

Returns the value for the specified entry.

Specified by:

get in interface Index

Parameters:

entryNum - number of the entry

Returns:

value value of the entry

set

public Index set(int entryNum,
                 int value)

Description copied from interface: Index

Returns a new index with the specified new value at the specified entry.

Specified by:

set in interface Index

Parameters:

entryNum - number of the entry

value - new value for the entry

Returns:

new index with the requested change

add

public Index add(int entryNum,
                 int add)

Description copied from interface: Index

Returns a new index with the specified increment at the specified entry.

Specified by:

add in interface Index

Parameters:

entryNum - number of the entry

add - increment for the entry, may be negative

Returns:

new index with the requested change

sum

public int sum()

Description copied from interface: Index

Returns the the sum of all entry values.

Specified by:

sum in interface Index

Returns:

length of the index

iterator

public java.util.Iterator<de.torstennahm.math.IntEntry> iterator()

Description copied from interface: Index

Returns an IntPairIterator for iterating over the index. The iterator skips all entries whose value is zero.

Specified by:

iterator in interface Index

Specified by:

iterator in interface java.lang.Iterable<de.torstennahm.math.IntEntry>

Returns:

iterator iterator over the non-zero entries

newHash

protected static int newHash(int hashCode,
                             int entryNum,
                             int oldVal,
                             int newVal)

hashCode

public int hashCode()

Description copied from interface: Index

Returns the hash code value for this index. The hash code of an index is defined by the following expression:
hashCode = e[0] * a0 + ... + e[dimension - 1] * a_(dimension-1)
, where e[i] is the i-th entry, and a_i = (i + 13) << i in integer arithmetic.

Specified by:

hashCode in interface Index

Overrides:

hashCode in class java.lang.Object

equals

public boolean equals(java.lang.Object o)

Description copied from interface: Index

Compares the specified object with this index for equality. Returns true if the specified object is also an index, the two indices have the same dimension, and all the entries of the two indices are equal. This definition ensures that the equals method works properly across different implementations of the Index interface.

Specified by:

equals in interface Index

Overrides:

equals in class java.lang.Object

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object