org.biojava.bio.alignment

Class NeedlemanWunsch

java.lang.Object

org.biojava.bio.alignment.AlignmentAlgorithm

org.biojava.bio.alignment.NeedlemanWunsch

public class NeedlemanWunsch
extends AlignmentAlgorithm

Needleman and Wunsch defined the problem of global sequence alignments, from the first till the last symbol of a sequence. This class is able to perform such global sequence comparisons efficiently by dynamic programming. If inserts and deletes are equally expensive and as expensive as the extension of a gap, the alignment method of this class does not use affine gap penalties. Otherwise it does. Those costs need four times as much memory, which has significant effects on the run time, if the computer needs to swap.

Since:

1.5

Author:

Andreas Dräger, Gero Greiner, Mark Schreiber

Field Summary

Fields

Modifier and Type	Field and Description
protected int[][]	CostMatrix A matrix with the size length(sequence1) times length(sequence2)
protected SubstitutionMatrix	subMatrix A matrix with the size length(alphabet) times length(alphabet)

Constructor Summary

Constructors

Constructor and Description
NeedlemanWunsch(short match, short replace, short insert, short delete, short gapExtend, SubstitutionMatrix subMat) Constructs a new Object with the given parameters based on the Needleman-Wunsch algorithm The alphabet of sequences to be aligned will be taken from the given substitution matrix.

Method Summary

Methods

Modifier and Type	Method and Description
short	getDelete() Returns the current expenses of a single delete operation.
int	getEditDistance() This gives the edit distance according to the given parameters of this certain object.
short	getGapExt() Returns the current expenses of any extension of a gap operation.
short	getInsert() Returns the current expenses of a single insert operation.
short	getMatch() Returns the current expenses of a single match operation.
short	getReplace() Returns the current expenses of a single replace operation.
protected static int	min(int x, int y, int z) This just computes the minimum of three integer values.
AlignmentPair	pairwiseAlignment(SymbolList query, SymbolList subject) Global pairwise sequence alignment of two BioJava-Sequence objects according to the Needleman-Wunsch-algorithm.
static String	printCostMatrix(int[][] CostMatrix, char[] queryChar, char[] targetChar) Prints a String representation of the CostMatrix for the given Alignment on the screen.
void	setDelete(short del) Sets the penalty for a delete operation to the specified value.
void	setGapExt(short ge) Sets the penalty for an extension of any gap (insert or delete) to the specified value.
void	setInsert(short ins) Sets the penalty for an insert operation to the specified value.
void	setMatch(short ma) Sets the penalty for a match operation to the specified value.
void	setReplace(short rep) Sets the penalty for a replace operation to the specified value.
void	setSubstitutionMatrix(SubstitutionMatrix matrix) Sets the substitution matrix to be used to the specified one.

Methods inherited from class org.biojava.bio.alignment.AlignmentAlgorithm

alignAll

Methods inherited from class java.lang.Object

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

Field Detail

CostMatrix

protected int[][] CostMatrix

A matrix with the size length(sequence1) times length(sequence2)

subMatrix

protected SubstitutionMatrix subMatrix

A matrix with the size length(alphabet) times length(alphabet)

Constructor Detail

NeedlemanWunsch

public NeedlemanWunsch(short match,
               short replace,
               short insert,
               short delete,
               short gapExtend,
               SubstitutionMatrix subMat)

Constructs a new Object with the given parameters based on the Needleman-Wunsch algorithm The alphabet of sequences to be aligned will be taken from the given substitution matrix.

Parameters:

match - This gives the costs for a match operation. It is only used, if there is no entry for a certain match of two symbols in the substitution matrix (default value).

replace - This is like the match parameter just the default, if there is no entry in the substitution matrix object.

insert - The costs of a single insert operation.

delete - The expenses of a single delete operation.

gapExtend - The expenses of an extension of a existing gap (that is a previous insert or delete. If the costs for insert and delete are equal and also equal to gapExtend, no affine gap penalties will be used, which saves a significant amount of memory.

subMat - The substitution matrix object which gives the costs for matches and replaces.

Method Detail

min

protected static int min(int x,
      int y,
      int z)

This just computes the minimum of three integer values.

Parameters:

x -

y -

z -

Returns:

Gives the minimum of three integers

printCostMatrix

public static String printCostMatrix(int[][] CostMatrix,
                     char[] queryChar,
                     char[] targetChar)

Prints a String representation of the CostMatrix for the given Alignment on the screen. This can be used to get a better understanding of the algorithm. There is no other purpose. This method also works for all extensions of this class with all kinds of matrices.

Parameters:

CostMatrix - The matrix that contains all expenses for swapping symbols.

queryChar - a character representation of the query sequence ( mySequence.seqString().toCharArray()).

targetChar - a character representation of the target sequence.

Returns:

a String representation of the matrix.

getDelete

public short getDelete()

Returns the current expenses of a single delete operation.

Returns:

delete

getEditDistance

public int getEditDistance()

This gives the edit distance according to the given parameters of this certain object. It returns just the last element of the internal cost matrix (left side down). So if you extend this class, you can just do the following: int myDistanceValue = foo; this.CostMatrix = new int[1][1]; this.CostMatrix[0][0] = myDistanceValue;

Returns:

returns the edit_distance computed with the given parameters.

getGapExt

public short getGapExt()

Returns the current expenses of any extension of a gap operation.

Returns:

gapExt

getInsert

public short getInsert()

Returns the current expenses of a single insert operation.

Returns:

insert

getMatch

public short getMatch()

Returns the current expenses of a single match operation.

Returns:

match

getReplace

public short getReplace()

Returns the current expenses of a single replace operation.

Returns:

replace

pairwiseAlignment

public AlignmentPair pairwiseAlignment(SymbolList query,
                              SymbolList subject)
                                throws BioException

Global pairwise sequence alignment of two BioJava-Sequence objects according to the Needleman-Wunsch-algorithm.

Specified by:

pairwiseAlignment in class AlignmentAlgorithm

Returns:

score of the alignment or the distance.

Throws:

BioException

See Also:

AlignmentAlgorithm.pairwiseAlignment(org.biojava.bio.symbol.SymbolList, org.biojava.bio.symbol.SymbolList)

setDelete

public void setDelete(short del)

Sets the penalty for a delete operation to the specified value.

Parameters:

del - costs for a single deletion operation

setGapExt

public void setGapExt(short ge)

Sets the penalty for an extension of any gap (insert or delete) to the specified value.

Parameters:

ge - costs for any gap extension

setInsert

public void setInsert(short ins)

Sets the penalty for an insert operation to the specified value.

Parameters:

ins - costs for a single insert operation

setMatch

public void setMatch(short ma)

Sets the penalty for a match operation to the specified value.

Parameters:

ma - costs for a single match operation

setReplace

public void setReplace(short rep)

Sets the penalty for a replace operation to the specified value.

Parameters:

rep - costs for a single replace operation

setSubstitutionMatrix

public void setSubstitutionMatrix(SubstitutionMatrix matrix)

Sets the substitution matrix to be used to the specified one. Afterwards it is only possible to align sequences of the alphabet of this substitution matrix.

Parameters:

matrix - an instance of a substitution matrix.