Class SparseObjectMatrix2D
- All Implemented Interfaces:
Serializable
,Cloneable
Implementation:
Note that this implementation is not synchronized.
Uses a OpenIntObjectHashMap
, which is a compact and performant hashing technique.
Memory requirements:
Cells that
- are never set to non-zero values do not use any memory.
- switch from zero to non-zero state do use memory.
- switch back from non-zero to zero state also do use memory. However, their memory is automatically reclaimed from time to time. It can also manually be reclaimed by calling
trimToSize()
.
worst case: memory [bytes] = (1/minLoadFactor) * nonZeros * 13.
best case: memory [bytes] = (1/maxLoadFactor) * nonZeros * 13.
Where nonZeros = cardinality() is the number of non-zero cells.
Thus, a 1000 x 1000 matrix with minLoadFactor=0.25 and maxLoadFactor=0.5 and 1000000 non-zero cells consumes between 25 MB and 50 MB.
The same 1000 x 1000 matrix with 1000 non-zero cells consumes between 25 and 50 KB.
Time complexity:
This class offers expected time complexity O(1) (i.e. constant time) for the basic operations
get, getQuick, set, setQuick and size
assuming the hash function disperses the elements properly among the buckets.
Otherwise, pathological cases, although highly improbable, can occur, degrading performance to O(N) in the worst case.
As such this sparse class is expected to have no worse time complexity than its dense counterpart DenseObjectMatrix2D
.
However, constant factors are considerably larger.
Cells are internally addressed in row-major. Performance sensitive applications can exploit this fact. Setting values in a loop row-by-row is quicker than column-by-column, because fewer hash collisions occur. Thus
for (int row=0; row invalid input: '<' rows; row++) { for (int column=0; column invalid input: '<' columns; column++) { matrix.setQuick(row,column,someValue); } }is quicker than
for (int column=0; column invalid input: '<' columns; column++) { for (int row=0; row invalid input: '<' rows; row++) { matrix.setQuick(row,column,someValue); } }
- Version:
- 1.0, 09/24/99
- See Also:
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Field Summary
FieldsFields inherited from class cern.colt.matrix.impl.AbstractMatrix2D
columns, columnStride, columnZero, rows, rowStride, rowZero
Fields inherited from class cern.colt.matrix.impl.AbstractMatrix
isNoView
Fields inherited from class cern.colt.PersistentObject
serialVersionUID
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Constructor Summary
ConstructorsModifierConstructorDescriptionSparseObjectMatrix2D
(int rows, int columns) Constructs a matrix with a given number of rows and columns and default memory usage.SparseObjectMatrix2D
(int rows, int columns, int initialCapacity, double minLoadFactor, double maxLoadFactor) Constructs a matrix with a given number of rows and columns using memory as specified.protected
SparseObjectMatrix2D
(int rows, int columns, AbstractIntObjectMap elements, int rowZero, int columnZero, int rowStride, int columnStride) Constructs a view with the given parameters.SparseObjectMatrix2D
(Object[][] values) Constructs a matrix with a copy of the given values. -
Method Summary
Modifier and TypeMethodDescriptionint
Returns the number of cells having non-zero values.void
ensureCapacity
(int minCapacity) Ensures that the receiver can hold at least the specified number of non-zero cells without needing to allocate new internal memory.getQuick
(int row, int column) Returns the matrix cell value at coordinate [row,column].protected boolean
haveSharedCellsRaw
(ObjectMatrix2D other) Returns true if both matrices share common cells.protected int
index
(int row, int column) Returns the position of the given coordinate within the (virtual or non-virtual) internal 1-dimensional array.like
(int rows, int columns) Construct and returns a new empty matrix of the same dynamic type as the receiver, having the specified number of rows and columns.like1D
(int size) Construct and returns a new 1-d matrix of the corresponding dynamic type, entirelly independent of the receiver.protected ObjectMatrix1D
like1D
(int size, int offset, int stride) Construct and returns a new 1-d matrix of the corresponding dynamic type, sharing the same cells.void
Sets the matrix cell at coordinate [row,column] to the specified value.void
Releases any superfluous memory created by explicitly putting zero values into cells formerly having non-zero values; An application can use this operation to minimize the storage of the receiver.protected ObjectMatrix2D
viewSelectionLike
(int[] rowOffsets, int[] columnOffsets) Construct and returns a new selection view.Methods inherited from class cern.colt.matrix.ObjectMatrix2D
aggregate, aggregate, assign, assign, assign, assign, assign, copy, equals, equals, get, getContent, getNonZeros, haveSharedCells, like, set, toArray, toString, view, viewColumn, viewColumnFlip, viewDice, viewPart, viewRow, viewRowFlip, viewSelection, viewSelection, viewSorted, viewStrides
Methods inherited from class cern.colt.matrix.impl.AbstractMatrix2D
_columnOffset, _columnRank, _rowOffset, _rowRank, checkBox, checkColumn, checkColumnIndexes, checkRow, checkRowIndexes, checkShape, checkShape, columns, rows, setUp, setUp, size, toStringShort, vColumnFlip, vDice, vPart, vRowFlip, vStrides
Methods inherited from class cern.colt.matrix.impl.AbstractMatrix
isView
Methods inherited from class cern.colt.PersistentObject
clone
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Field Details
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elements
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Constructor Details
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SparseObjectMatrix2D
Constructs a matrix with a copy of the given values. values is required to have the form values[row][column] and have exactly the same number of columns in every row.The values are copied. So subsequent changes in values are not reflected in the matrix, and vice-versa.
- Parameters:
values
- The values to be filled into the new matrix.- Throws:
IllegalArgumentException
- if for any 1 <= row < values.length: values[row].length != values[row-1].length.
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SparseObjectMatrix2D
public SparseObjectMatrix2D(int rows, int columns) Constructs a matrix with a given number of rows and columns and default memory usage. All entries are initially null.- Parameters:
rows
- the number of rows the matrix shall have.columns
- the number of columns the matrix shall have.- Throws:
IllegalArgumentException
- if rowsinvalid input: '<'0 || columnsinvalid input: '<'0 || (double)columns*rows > Integer.MAX_VALUE.
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SparseObjectMatrix2D
public SparseObjectMatrix2D(int rows, int columns, int initialCapacity, double minLoadFactor, double maxLoadFactor) Constructs a matrix with a given number of rows and columns using memory as specified. All entries are initially null. For details related to memory usage seeOpenIntObjectHashMap
.- Parameters:
rows
- the number of rows the matrix shall have.columns
- the number of columns the matrix shall have.initialCapacity
- the initial capacity of the hash map. If not known, set initialCapacity=0 or small.minLoadFactor
- the minimum load factor of the hash map.maxLoadFactor
- the maximum load factor of the hash map.- Throws:
IllegalArgumentException
- if initialCapacity invalid input: '<' 0 || (minLoadFactor invalid input: '<' 0.0 || minLoadFactor >= 1.0) || (maxLoadFactor invalid input: '<'= 0.0 || maxLoadFactor >= 1.0) || (minLoadFactor >= maxLoadFactor).IllegalArgumentException
- if rowsinvalid input: '<'0 || columnsinvalid input: '<'0 || (double)columns*rows > Integer.MAX_VALUE.
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SparseObjectMatrix2D
protected SparseObjectMatrix2D(int rows, int columns, AbstractIntObjectMap elements, int rowZero, int columnZero, int rowStride, int columnStride) Constructs a view with the given parameters.- Parameters:
rows
- the number of rows the matrix shall have.columns
- the number of columns the matrix shall have.elements
- the cells.rowZero
- the position of the first element.columnZero
- the position of the first element.rowStride
- the number of elements between two rows, i.e. index(i+1,j)-index(i,j).columnStride
- the number of elements between two columns, i.e. index(i,j+1)-index(i,j).- Throws:
IllegalArgumentException
- if rowsinvalid input: '<'0 || columnsinvalid input: '<'0 || (double)columns*rows > Integer.MAX_VALUE or flip's are illegal.
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Method Details
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cardinality
public int cardinality()Returns the number of cells having non-zero values.- Overrides:
cardinality
in classObjectMatrix2D
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ensureCapacity
public void ensureCapacity(int minCapacity) Ensures that the receiver can hold at least the specified number of non-zero cells without needing to allocate new internal memory. If necessary, allocates new internal memory and increases the capacity of the receiver.This method never need be called; it is for performance tuning only. Calling this method before tt>set()ing a large number of non-zero values boosts performance, because the receiver will grow only once instead of potentially many times and hash collisions get less probable.
- Overrides:
ensureCapacity
in classAbstractMatrix
- Parameters:
minCapacity
- the desired minimum number of non-zero (non-null) cells.minNonZeros
- the desired minimum number of non-zero cells.
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getQuick
Returns the matrix cell value at coordinate [row,column].Provided with invalid parameters this method may return invalid objects without throwing any exception. You should only use this method when you are absolutely sure that the coordinate is within bounds. Precondition (unchecked): 0 <= column < columns() invalid input: '&'invalid input: '&' 0 <= row < rows().
- Specified by:
getQuick
in classObjectMatrix2D
- Parameters:
row
- the index of the row-coordinate.column
- the index of the column-coordinate.- Returns:
- the value at the specified coordinate.
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index
protected int index(int row, int column) Returns the position of the given coordinate within the (virtual or non-virtual) internal 1-dimensional array.- Overrides:
index
in classAbstractMatrix2D
- Parameters:
row
- the index of the row-coordinate.column
- the index of the column-coordinate.
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like
Construct and returns a new empty matrix of the same dynamic type as the receiver, having the specified number of rows and columns. For example, if the receiver is an instance of type DenseObjectMatrix2D the new matrix must also be of type DenseObjectMatrix2D, if the receiver is an instance of type SparseObjectMatrix2D the new matrix must also be of type SparseObjectMatrix2D, etc. In general, the new matrix should have internal parametrization as similar as possible.- Specified by:
like
in classObjectMatrix2D
- Parameters:
rows
- the number of rows the matrix shall have.columns
- the number of columns the matrix shall have.- Returns:
- a new empty matrix of the same dynamic type.
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like1D
Construct and returns a new 1-d matrix of the corresponding dynamic type, entirelly independent of the receiver. For example, if the receiver is an instance of type DenseObjectMatrix2D the new matrix must be of type DenseObjectMatrix1D, if the receiver is an instance of type SparseObjectMatrix2D the new matrix must be of type SparseObjectMatrix1D, etc.- Specified by:
like1D
in classObjectMatrix2D
- Parameters:
size
- the number of cells the matrix shall have.- Returns:
- a new matrix of the corresponding dynamic type.
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like1D
Construct and returns a new 1-d matrix of the corresponding dynamic type, sharing the same cells. For example, if the receiver is an instance of type DenseObjectMatrix2D the new matrix must be of type DenseObjectMatrix1D, if the receiver is an instance of type SparseObjectMatrix2D the new matrix must be of type SparseObjectMatrix1D, etc.- Specified by:
like1D
in classObjectMatrix2D
- Parameters:
size
- the number of cells the matrix shall have.offset
- the index of the first element.stride
- the number of indexes between any two elements, i.e. index(i+1)-index(i).- Returns:
- a new matrix of the corresponding dynamic type.
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setQuick
Sets the matrix cell at coordinate [row,column] to the specified value.Provided with invalid parameters this method may access illegal indexes without throwing any exception. You should only use this method when you are absolutely sure that the coordinate is within bounds. Precondition (unchecked): 0 <= column < columns() invalid input: '&'invalid input: '&' 0 <= row < rows().
- Specified by:
setQuick
in classObjectMatrix2D
- Parameters:
row
- the index of the row-coordinate.column
- the index of the column-coordinate.value
- the value to be filled into the specified cell.
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trimToSize
public void trimToSize()Releases any superfluous memory created by explicitly putting zero values into cells formerly having non-zero values; An application can use this operation to minimize the storage of the receiver.Background:
Cells that
- are never set to non-zero values do not use any memory.
- switch from zero to non-zero state do use memory.
- switch back from non-zero to zero state also do use memory. However, their memory can be reclaimed by calling trimToSize().
- Overrides:
trimToSize
in classAbstractMatrix
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viewSelectionLike
Construct and returns a new selection view.- Specified by:
viewSelectionLike
in classObjectMatrix2D
- Parameters:
rowOffsets
- the offsets of the visible elements.columnOffsets
- the offsets of the visible elements.- Returns:
- a new view.
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