Class BitMatrix
- java.lang.Object
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- cern.colt.PersistentObject
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- cern.colt.bitvector.BitMatrix
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- All Implemented Interfaces:
java.io.Serializable
,java.lang.Cloneable
public class BitMatrix extends PersistentObject
Fixed sized (non resizable) n*m bit matrix. A bit matrix has a number of columns and rows, which are assigned upon instance construction - The matrix's size is then columns()*rows(). Bits are accessed via (column,row) coordinates.Individual bits can be examined, set, or cleared. Rectangular parts (boxes) can quickly be extracted, copied and replaced. Quick iteration over boxes is provided by optimized internal iterators (forEach() methods). One
BitMatrix
may be used to modify the contents of anotherBitMatrix
through logical AND, OR, XOR and other similar operations.Legal coordinates range from [0,0] to [columns()-1,rows()-1]. Any attempt to access a bit at a coordinate column<0 || column>=columns() || row<0 || row>=rows() will throw an IndexOutOfBoundsException. Operations involving two bit matrices (like AND, OR, XOR, etc.) will throw an IllegalArgumentException if both bit matrices do not have the same number of columns and rows.
If you need extremely quick access to individual bits: Although getting and setting individual bits with methods get(...) and put(...) is quick, it is even quicker (but not safe) to use getQuick(...) and putQuick(...).
Note that this implementation is not synchronized.
- Version:
- 1.0, 09/24/99
- See Also:
BitVector
,QuickBitVector
,BitSet
, Serialized Form
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Field Summary
Fields Modifier and Type Field Description protected long[]
bits
protected int
columns
protected int
rows
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Fields inherited from class cern.colt.PersistentObject
serialVersionUID
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Constructor Summary
Constructors Constructor Description BitMatrix(int columns, int rows)
Constructs a bit matrix with a given number of columns and rows.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
and(BitMatrix other)
Performs a logical AND of the receiver with another bit matrix.void
andNot(BitMatrix other)
Clears all of the bits in receiver whose corresponding bit is set in the other bit matrix.int
cardinality()
Returns the number of bits currently in the true state.protected void
checkDimensionCompatibility(BitMatrix other)
Sanity check for operations requiring matrices with the same number of columns and rows.void
clear()
Clears all bits of the receiver.java.lang.Object
clone()
Cloning thisBitMatrix
produces a newBitMatrix
that is equal to it.int
columns()
Returns the number of columns of the receiver.protected void
containsBox(int column, int row, int width, int height)
Checks whether the receiver contains the given box.BitMatrix
copy()
Returns a shallow clone of the receiver; callsclone()
and casts the result.protected long[]
elements()
protected void
elements(long[] bits, int columns, int rows)
You normally need not use this method.boolean
equals(java.lang.Object obj)
Compares this object against the specified object.boolean
forEachCoordinateInState(boolean state, IntIntProcedure procedure)
Applies a procedure to each coordinate that holds a bit in the given state.boolean
get(int column, int row)
Returns from the receiver the value of the bit at the specified coordinate.boolean
getQuick(int column, int row)
Returns from the receiver the value of the bit at the specified coordinate; WARNING: Does not check preconditions.int
hashCode()
Returns a hash code value for the receiver.void
not()
Performs a logical NOT on the bits of the receiver.void
or(BitMatrix other)
Performs a logical OR of the receiver with another bit matrix.BitMatrix
part(int column, int row, int width, int height)
Constructs and returns a new matrix with width columns and height rows which is a copy of the contents of the given box.void
put(int column, int row, boolean value)
Sets the bit at the specified coordinate to the state specified by value.void
putQuick(int column, int row, boolean value)
Sets the bit at the specified coordinate to the state specified by value; WARNING: Does not check preconditions.void
replaceBoxWith(int column, int row, int width, int height, boolean value)
Sets the bits in the given box to the state specified by value.void
replaceBoxWith(int column, int row, int width, int height, BitMatrix source, int sourceColumn, int sourceRow)
Replaces a box of the receiver with the contents of another matrix's box.int
rows()
Returns the number of rows of the receiver.int
size()
Returns the size of the receiver which is columns()*rows().BitVector
toBitVector()
Converts the receiver to a bitvector.java.lang.String
toString()
Returns a (very crude) string representation of the receiver.void
xor(BitMatrix other)
Performs a logical XOR of the receiver with another bit matrix.
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Constructor Detail
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BitMatrix
public BitMatrix(int columns, int rows)
Constructs a bit matrix with a given number of columns and rows. All bits are initially false.- Parameters:
columns
- the number of columns the matrix shall have.rows
- the number of rows the matrix shall have.- Throws:
java.lang.IllegalArgumentException
- if columns < 0 || rows < 0.
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Method Detail
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and
public void and(BitMatrix other)
Performs a logical AND of the receiver with another bit matrix. The receiver is modified so that a bit in it has the valuetrue
if and only if it already had the valuetrue
and the corresponding bit in the other bit matrix argument has the valuetrue
.- Parameters:
other
- a bit matrix.- Throws:
java.lang.IllegalArgumentException
- if columns() != other.columns() || rows() != other.rows().
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andNot
public void andNot(BitMatrix other)
Clears all of the bits in receiver whose corresponding bit is set in the other bit matrix. In other words, determines the difference (A\B) between two bit matrices.- Parameters:
other
- a bit matrix with which to mask the receiver.- Throws:
java.lang.IllegalArgumentException
- if columns() != other.columns() || rows() != other.rows().
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cardinality
public int cardinality()
Returns the number of bits currently in the true state. Optimized for speed. Particularly quick if the receiver is either sparse or dense.
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checkDimensionCompatibility
protected void checkDimensionCompatibility(BitMatrix other)
Sanity check for operations requiring matrices with the same number of columns and rows.
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clear
public void clear()
Clears all bits of the receiver.
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clone
public java.lang.Object clone()
Cloning thisBitMatrix
produces a newBitMatrix
that is equal to it. The clone of the bit matrix is another bit matrix that has exactly the same bits set totrue
as this bit matrix and the same number of columns and rows.- Overrides:
clone
in classPersistentObject
- Returns:
- a clone of this bit matrix.
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columns
public int columns()
Returns the number of columns of the receiver.
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containsBox
protected void containsBox(int column, int row, int width, int height)
Checks whether the receiver contains the given box.
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copy
public BitMatrix copy()
Returns a shallow clone of the receiver; callsclone()
and casts the result.- Returns:
- a shallow clone of the receiver.
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elements
protected long[] elements()
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elements
protected void elements(long[] bits, int columns, int rows)
You normally need not use this method. Use this method only if performance is critical. Sets the bit matrix's backing bits, columns and rows. WARNING: For efficiency reasons and to keep memory usage low, the array is not copied. So if subsequently you modify the specified array directly via the [] operator, be sure you know what you're doing.- Throws:
java.lang.IllegalArgumentException
- if columns < 0 || rows < 0 || columns*rows > bits.length*64
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equals
public boolean equals(java.lang.Object obj)
Compares this object against the specified object. The result istrue
if and only if the argument is notnull
and is aBitMatrix
object that has the same number of columns and rows as the receiver and that has exactly the same bits set totrue
as the receiver.- Overrides:
equals
in classjava.lang.Object
- Parameters:
obj
- the object to compare with.- Returns:
true
if the objects are the same;false
otherwise.
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forEachCoordinateInState
public boolean forEachCoordinateInState(boolean state, IntIntProcedure procedure)
Applies a procedure to each coordinate that holds a bit in the given state. Iterates rowwise downwards from [columns()-1,rows()-1] to [0,0]. Useful, for example, if you want to copy bits into an image or somewhere else. Optimized for speed. Particularly quick if one of the following conditions holds- state==true and the receiver is sparse (cardinality() is small compared to size()).
- state==false and the receiver is dense (cardinality() is large compared to size()).
- Parameters:
state
- element to search for.procedure
- a procedure object taking as first argument the current column and as second argument the current row. Stops iteration if the procedure returns false, otherwise continues.- Returns:
- false if the procedure stopped before all elements where iterated over, true otherwise.
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get
public boolean get(int column, int row)
Returns from the receiver the value of the bit at the specified coordinate. The value is true if this bit is currently set; otherwise, returns false.- Parameters:
column
- the index of the column-coordinate.row
- the index of the row-coordinate.- Returns:
- the value of the bit at the specified coordinate.
- Throws:
java.lang.IndexOutOfBoundsException
- if column<0 || column>=columns() || row<0 || row>=rows()
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getQuick
public boolean getQuick(int column, int row)
Returns from the receiver the value of the bit at the specified coordinate; WARNING: Does not check preconditions. The value is true if this bit is currently set; otherwise, returns false.Provided with invalid parameters this method may return invalid values without throwing any exception. You should only use this method when you are absolutely sure that the coordinate is within bounds. Precondition (unchecked): column>=0 && column<columns() && row>=0 && row<rows().
- Parameters:
column
- the index of the column-coordinate.row
- the index of the row-coordinate.- Returns:
- the value of the bit at the specified coordinate.
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hashCode
public int hashCode()
Returns a hash code value for the receiver.- Overrides:
hashCode
in classjava.lang.Object
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not
public void not()
Performs a logical NOT on the bits of the receiver.
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or
public void or(BitMatrix other)
Performs a logical OR of the receiver with another bit matrix. The receiver is modified so that a bit in it has the valuetrue
if and only if it either already had the valuetrue
or the corresponding bit in the other bit matrix argument has the valuetrue
.- Parameters:
other
- a bit matrix.- Throws:
java.lang.IllegalArgumentException
- if columns() != other.columns() || rows() != other.rows().
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part
public BitMatrix part(int column, int row, int width, int height)
Constructs and returns a new matrix with width columns and height rows which is a copy of the contents of the given box. The box ranges from [column,row] to [column+width-1,row+height-1], all inclusive.- Parameters:
column
- the index of the column-coordinate.row
- the index of the row-coordinate.width
- the width of the box.height
- the height of the box.- Throws:
java.lang.IndexOutOfBoundsException
- if column<0 || column+width>columns() || row<0 || row+height>rows()
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put
public void put(int column, int row, boolean value)
Sets the bit at the specified coordinate to the state specified by value.- Parameters:
column
- the index of the column-coordinate.row
- the index of the row-coordinate.value
- the value of the bit to be copied into the specified coordinate.- Throws:
java.lang.IndexOutOfBoundsException
- if column<0 || column>=columns() || row<0 || row>=rows()
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putQuick
public void putQuick(int column, int row, boolean value)
Sets the bit at the specified coordinate to the state specified by value; WARNING: Does not check preconditions.Provided with invalid parameters this method may return invalid values without throwing any exception. You should only use this method when you are absolutely sure that the coordinate is within bounds. Precondition (unchecked): column>=0 && column<columns() && row>=0 && row<rows().
- Parameters:
column
- the index of the column-coordinate.row
- the index of the row-coordinate.value
- the value of the bit to be copied into the specified coordinate.
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replaceBoxWith
public void replaceBoxWith(int column, int row, int width, int height, BitMatrix source, int sourceColumn, int sourceRow)
Replaces a box of the receiver with the contents of another matrix's box. The source box ranges from [sourceColumn,sourceRow] to [sourceColumn+width-1,sourceRow+height-1], all inclusive. The destination box ranges from [column,row] to [column+width-1,row+height-1], all inclusive. Does nothing if width <= 0 || height <= 0. If source==this and the source and destination box intersect in an ambiguous way, then replaces as if using an intermediate auxiliary copy of the receiver.- Parameters:
column
- the index of the column-coordinate.row
- the index of the row-coordinate.width
- the width of the box.height
- the height of the box.source
- the source matrix to copy from(may be identical to the receiver).sourceColumn
- the index of the source column-coordinate.sourceRow
- the index of the source row-coordinate.- Throws:
java.lang.IndexOutOfBoundsException
- if column<0 || column+width>columns() || row<0 || row+height>rows()java.lang.IndexOutOfBoundsException
- if sourceColumn<0 || sourceColumn+width>source.columns() || sourceRow<0 || sourceRow+height>source.rows()
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replaceBoxWith
public void replaceBoxWith(int column, int row, int width, int height, boolean value)
Sets the bits in the given box to the state specified by value. The box ranges from [column,row] to [column+width-1,row+height-1], all inclusive. (Does nothing if width <= 0 || height <= 0).- Parameters:
column
- the index of the column-coordinate.row
- the index of the row-coordinate.width
- the width of the box.height
- the height of the box.value
- the value of the bit to be copied into the bits of the specified box.- Throws:
java.lang.IndexOutOfBoundsException
- if column<0 || column+width>columns() || row<0 || row+height>rows()
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rows
public int rows()
Returns the number of rows of the receiver.
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size
public int size()
Returns the size of the receiver which is columns()*rows().
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toBitVector
public BitVector toBitVector()
Converts the receiver to a bitvector. In many cases this method only makes sense on one-dimensional matrices. WARNING: The returned bitvector and the receiver share the same backing bits. Modifying either of them will affect the other. If this behaviour is not what you want, you should first use copy() to make sure both objects use separate internal storage.
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toString
public java.lang.String toString()
Returns a (very crude) string representation of the receiver.- Overrides:
toString
in classjava.lang.Object
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xor
public void xor(BitMatrix other)
Performs a logical XOR of the receiver with another bit matrix. The receiver is modified so that a bit in it has the valuetrue
if and only if one of the following statements holds:- The bit initially has the value
true
, and the corresponding bit in the argument has the valuefalse
. - The bit initially has the value
false
, and the corresponding bit in the argument has the valuetrue
.
- Parameters:
other
- a bit matrix.- Throws:
java.lang.IllegalArgumentException
- if columns() != other.columns() || rows() != other.rows().
- The bit initially has the value
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