Class DoubleMatrix2D
- java.lang.Object
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- cern.colt.PersistentObject
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- cern.colt.matrix.impl.AbstractMatrix
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- cern.colt.matrix.impl.AbstractMatrix2D
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- cern.colt.matrix.DoubleMatrix2D
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- All Implemented Interfaces:
java.io.Serializable
,java.lang.Cloneable
- Direct Known Subclasses:
DenseDoubleMatrix2D
,SelectedDenseDoubleMatrix2D
,SelectedSparseDoubleMatrix2D
,SparseDoubleMatrix2D
,WrapperDoubleMatrix2D
public abstract class DoubleMatrix2D extends AbstractMatrix2D
Abstract base class for 2-d matrices holding double elements. First see the package summary and javadoc tree view to get the broad picture.A matrix has a number of rows and columns, which are assigned upon instance construction - The matrix's size is then rows()*columns(). Elements are accessed via [row,column] coordinates. Legal coordinates range from [0,0] to [rows()-1,columns()-1]. Any attempt to access an element at a coordinate column<0 || column>=columns() || row<0 || row>=rows() will throw an IndexOutOfBoundsException.
Note that this implementation is not synchronized.
- Version:
- 1.0, 09/24/99
- See Also:
- Serialized Form
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Field Summary
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Fields inherited from class cern.colt.matrix.impl.AbstractMatrix2D
columns, columnStride, columnZero, rows, rowStride, rowZero
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Fields inherited from class cern.colt.matrix.impl.AbstractMatrix
isNoView
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Fields inherited from class cern.colt.PersistentObject
serialVersionUID
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Constructor Summary
Constructors Modifier Constructor Description protected
DoubleMatrix2D()
Makes this class non instantiable, but still let's others inherit from it.
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Method Summary
All Methods Instance Methods Abstract Methods Concrete Methods Modifier and Type Method Description double
aggregate(DoubleDoubleFunction aggr, DoubleFunction f)
Applies a function to each cell and aggregates the results.double
aggregate(DoubleMatrix2D other, DoubleDoubleFunction aggr, DoubleDoubleFunction f)
Applies a function to each corresponding cell of two matrices and aggregates the results.DoubleMatrix2D
assign(double value)
Sets all cells to the state specified by value.DoubleMatrix2D
assign(double[][] values)
Sets all cells to the state specified by values.DoubleMatrix2D
assign(DoubleFunction function)
Assigns the result of a function to each cell; x[row,col] = function(x[row,col]).DoubleMatrix2D
assign(DoubleMatrix2D other)
Replaces all cell values of the receiver with the values of another matrix.DoubleMatrix2D
assign(DoubleMatrix2D y, DoubleDoubleFunction function)
Assigns the result of a function to each cell; x[row,col] = function(x[row,col],y[row,col]).int
cardinality()
Returns the number of cells having non-zero values; ignores tolerance.DoubleMatrix2D
copy()
Constructs and returns a deep copy of the receiver.boolean
equals(double value)
Returns whether all cells are equal to the given value.boolean
equals(java.lang.Object obj)
Compares this object against the specified object.DoubleMatrix2D
forEachNonZero(IntIntDoubleFunction function)
Assigns the result of a function to each non-zero cell; x[row,col] = function(x[row,col]).double
get(int row, int column)
Returns the matrix cell value at coordinate [row,column].protected DoubleMatrix2D
getContent()
Returns the content of this matrix if it is a wrapper; or this otherwise.void
getNonZeros(IntArrayList rowList, IntArrayList columnList, DoubleArrayList valueList)
Fills the coordinates and values of cells having non-zero values into the specified lists.abstract double
getQuick(int row, int column)
Returns the matrix cell value at coordinate [row,column].protected boolean
haveSharedCells(DoubleMatrix2D other)
Returns true if both matrices share at least one identical cell.protected boolean
haveSharedCellsRaw(DoubleMatrix2D other)
Returns true if both matrices share at least one identical cell.DoubleMatrix2D
like()
Construct and returns a new empty matrix of the same dynamic type as the receiver, having the same number of rows and columns.abstract DoubleMatrix2D
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.abstract DoubleMatrix1D
like1D(int size)
Construct and returns a new 1-d matrix of the corresponding dynamic type, entirelly independent of the receiver.protected abstract DoubleMatrix1D
like1D(int size, int zero, int stride)
Construct and returns a new 1-d matrix of the corresponding dynamic type, sharing the same cells.void
set(int row, int column, double value)
Sets the matrix cell at coordinate [row,column] to the specified value.abstract void
setQuick(int row, int column, double value)
Sets the matrix cell at coordinate [row,column] to the specified value.double[][]
toArray()
Constructs and returns a 2-dimensional array containing the cell values.java.lang.String
toString()
Returns a string representation using default formatting.protected DoubleMatrix2D
view()
Constructs and returns a new view equal to the receiver.DoubleMatrix1D
viewColumn(int column)
Constructs and returns a new slice view representing the rows of the given column.DoubleMatrix2D
viewColumnFlip()
Constructs and returns a new flip view along the column axis.DoubleMatrix2D
viewDice()
Constructs and returns a new dice (transposition) view; Swaps axes; example: 3 x 4 matrix --> 4 x 3 matrix.DoubleMatrix2D
viewPart(int row, int column, int height, int width)
Constructs and returns a new sub-range view that is a height x width sub matrix starting at [row,column].DoubleMatrix1D
viewRow(int row)
Constructs and returns a new slice view representing the columns of the given row.DoubleMatrix2D
viewRowFlip()
Constructs and returns a new flip view along the row axis.DoubleMatrix2D
viewSelection(int[] rowIndexes, int[] columnIndexes)
Constructs and returns a new selection view that is a matrix holding the indicated cells.DoubleMatrix2D
viewSelection(DoubleMatrix1DProcedure condition)
Constructs and returns a new selection view that is a matrix holding all rows matching the given condition.protected abstract DoubleMatrix2D
viewSelectionLike(int[] rowOffsets, int[] columnOffsets)
Construct and returns a new selection view.DoubleMatrix2D
viewSorted(int column)
Sorts the matrix rows into ascending order, according to the natural ordering of the matrix values in the given column.DoubleMatrix2D
viewStrides(int rowStride, int columnStride)
Constructs and returns a new stride view which is a sub matrix consisting of every i-th cell.private boolean
xforEach(DoubleProcedure procedure)
Applies a procedure to each cell's value.void
zAssign8Neighbors(DoubleMatrix2D B, Double9Function function)
8 neighbor stencil transformation.DoubleMatrix1D
zMult(DoubleMatrix1D y, DoubleMatrix1D z)
Linear algebraic matrix-vector multiplication; z = A * y; Equivalent to return A.zMult(y,z,1,0);DoubleMatrix1D
zMult(DoubleMatrix1D y, DoubleMatrix1D z, double alpha, double beta, boolean transposeA)
Linear algebraic matrix-vector multiplication; z = alpha * A * y + beta*z.DoubleMatrix2D
zMult(DoubleMatrix2D B, DoubleMatrix2D C)
Linear algebraic matrix-matrix multiplication; C = A x B; Equivalent to A.zMult(B,C,1,0,false,false).DoubleMatrix2D
zMult(DoubleMatrix2D B, DoubleMatrix2D C, double alpha, double beta, boolean transposeA, boolean transposeB)
Linear algebraic matrix-matrix multiplication; C = alpha * A x B + beta*C.double
zSum()
Returns the sum of all cells; Sum( x[i,j] ).-
Methods inherited from class cern.colt.matrix.impl.AbstractMatrix2D
_columnOffset, _columnRank, _rowOffset, _rowRank, checkBox, checkColumn, checkColumnIndexes, checkRow, checkRowIndexes, checkShape, checkShape, columns, index, rows, setUp, setUp, size, toStringShort, vColumnFlip, vDice, vPart, vRowFlip, vStrides
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Methods inherited from class cern.colt.matrix.impl.AbstractMatrix
ensureCapacity, isView, trimToSize
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Methods inherited from class cern.colt.PersistentObject
clone
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Method Detail
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aggregate
public double aggregate(DoubleDoubleFunction aggr, DoubleFunction f)
Applies a function to each cell and aggregates the results. Returns a value v such that v==a(size()) where a(i) == aggr( a(i-1), f(get(row,column)) ) and terminators are a(1) == f(get(0,0)), a(0)==Double.NaN.Example:
cern.jet.math.Functions F = cern.jet.math.Functions.functions; 2 x 2 matrix 0 1 2 3 // Sum( x[row,col]*x[row,col] ) matrix.aggregate(F.plus,F.square); --> 14
For further examples, see the package doc.- Parameters:
aggr
- an aggregation function taking as first argument the current aggregation and as second argument the transformed current cell value.f
- a function transforming the current cell value.- Returns:
- the aggregated measure.
- See Also:
Functions
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aggregate
public double aggregate(DoubleMatrix2D other, DoubleDoubleFunction aggr, DoubleDoubleFunction f)
Applies a function to each corresponding cell of two matrices and aggregates the results. Returns a value v such that v==a(size()) where a(i) == aggr( a(i-1), f(get(row,column),other.get(row,column)) ) and terminators are a(1) == f(get(0,0),other.get(0,0)), a(0)==Double.NaN.Example:
cern.jet.math.Functions F = cern.jet.math.Functions.functions; x == 2 x 2 matrix 0 1 2 3 y == 2 x 2 matrix 0 1 2 3 // Sum( x[row,col] * y[row,col] ) x.aggregate(y, F.plus, F.mult); --> 14 // Sum( (x[row,col] + y[row,col])^2 ) x.aggregate(y, F.plus, F.chain(F.square,F.plus)); --> 56
For further examples, see the package doc.- Parameters:
aggr
- an aggregation function taking as first argument the current aggregation and as second argument the transformed current cell values.f
- a function transforming the current cell values.- Returns:
- the aggregated measure.
- Throws:
java.lang.IllegalArgumentException
- if columns() != other.columns() || rows() != other.rows()- See Also:
Functions
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assign
public DoubleMatrix2D assign(double[][] values)
Sets all cells to the state specified by values. values is required to have the form values[row][column] and have exactly the same number of rows and columns as the receiver.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 cells.- Returns:
- this (for convenience only).
- Throws:
java.lang.IllegalArgumentException
- if values.length != rows() || for any 0 <= row < rows(): values[row].length != columns().
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assign
public DoubleMatrix2D assign(double value)
Sets all cells to the state specified by value.- Parameters:
value
- the value to be filled into the cells.- Returns:
- this (for convenience only).
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assign
public DoubleMatrix2D assign(DoubleFunction function)
Assigns the result of a function to each cell; x[row,col] = function(x[row,col]).Example:
matrix = 2 x 2 matrix 0.5 1.5 2.5 3.5 // change each cell to its sine matrix.assign(cern.jet.math.Functions.sin); --> 2 x 2 matrix 0.479426 0.997495 0.598472 -0.350783
For further examples, see the package doc.- Parameters:
function
- a function object taking as argument the current cell's value.- Returns:
- this (for convenience only).
- See Also:
Functions
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assign
public DoubleMatrix2D assign(DoubleMatrix2D other)
Replaces all cell values of the receiver with the values of another matrix. Both matrices must have the same number of rows and columns. If both matrices share the same cells (as is the case if they are views derived from the same matrix) and intersect in an ambiguous way, then replaces as if using an intermediate auxiliary deep copy of other.- Parameters:
other
- the source matrix to copy from (may be identical to the receiver).- Returns:
- this (for convenience only).
- Throws:
java.lang.IllegalArgumentException
- if columns() != other.columns() || rows() != other.rows()
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assign
public DoubleMatrix2D assign(DoubleMatrix2D y, DoubleDoubleFunction function)
Assigns the result of a function to each cell; x[row,col] = function(x[row,col],y[row,col]).Example:
// assign x[row,col] = x[row,col]y[row,col] m1 = 2 x 2 matrix 0 1 2 3 m2 = 2 x 2 matrix 0 2 4 6 m1.assign(m2, cern.jet.math.Functions.pow); --> m1 == 2 x 2 matrix 1 1 16 729
For further examples, see the package doc.- Parameters:
y
- the secondary matrix to operate on.function
- a function object taking as first argument the current cell's value of this, and as second argument the current cell's value of y,- Returns:
- this (for convenience only).
- Throws:
java.lang.IllegalArgumentException
- if columns() != other.columns() || rows() != other.rows()- See Also:
Functions
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cardinality
public int cardinality()
Returns the number of cells having non-zero values; ignores tolerance.
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copy
public DoubleMatrix2D copy()
Constructs and returns a deep copy of the receiver.Note that the returned matrix is an independent deep copy. The returned matrix is not backed by this matrix, so changes in the returned matrix are not reflected in this matrix, and vice-versa.
- Returns:
- a deep copy of the receiver.
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equals
public boolean equals(double value)
Returns whether all cells are equal to the given value.- Parameters:
value
- the value to test against.- Returns:
- true if all cells are equal to the given value, false otherwise.
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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 at least aDoubleMatrix2D
object that has the same number of columns and rows as the receiver and has exactly the same values at the same coordinates.- 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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forEachNonZero
public DoubleMatrix2D forEachNonZero(IntIntDoubleFunction function)
Assigns the result of a function to each non-zero cell; x[row,col] = function(x[row,col]). Use this method for fast special-purpose iteration. If you want to modify another matrix instead of this (i.e. work in read-only mode), simply return the input value unchanged. Parameters to function are as follows: first==row, second==column, third==nonZeroValue.- Parameters:
function
- a function object taking as argument the current non-zero cell's row, column and value.- Returns:
- this (for convenience only).
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get
public double get(int row, int column)
Returns the matrix cell value at coordinate [row,column].- Parameters:
row
- the index of the row-coordinate.column
- the index of the column-coordinate.- Returns:
- the value of the specified cell.
- Throws:
java.lang.IndexOutOfBoundsException
- if column<0 || column>=columns() || row<0 || row>=rows()
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getContent
protected DoubleMatrix2D getContent()
Returns the content of this matrix if it is a wrapper; or this otherwise. Override this method in wrappers.
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getNonZeros
public void getNonZeros(IntArrayList rowList, IntArrayList columnList, DoubleArrayList valueList)
Fills the coordinates and values of cells having non-zero values into the specified lists. Fills into the lists, starting at index 0. After this call returns the specified lists all have a new size, the number of non-zero values.In general, fill order is unspecified. This implementation fills like for (row = 0..rows-1) for (column = 0..columns-1) do ... . However, subclasses are free to us any other order, even an order that may change over time as cell values are changed. (Of course, result lists indexes are guaranteed to correspond to the same cell).
Example:
2 x 3 matrix: 0, 0, 8 0, 7, 0 --> rowList = (0,1) columnList = (2,1) valueList = (8,7)
In other words, get(0,2)==8, get(1,1)==7.- Parameters:
rowList
- the list to be filled with row indexes, can have any size.columnList
- the list to be filled with column indexes, can have any size.valueList
- the list to be filled with values, can have any size.
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getQuick
public abstract double getQuick(int row, int column)
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() && 0 <= row < rows().
- 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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haveSharedCells
protected boolean haveSharedCells(DoubleMatrix2D other)
Returns true if both matrices share at least one identical cell.
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haveSharedCellsRaw
protected boolean haveSharedCellsRaw(DoubleMatrix2D other)
Returns true if both matrices share at least one identical cell.
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like
public DoubleMatrix2D like()
Construct and returns a new empty matrix of the same dynamic type as the receiver, having the same number of rows and columns. For example, if the receiver is an instance of type DenseDoubleMatrix2D the new matrix must also be of type DenseDoubleMatrix2D, if the receiver is an instance of type SparseDoubleMatrix2D the new matrix must also be of type SparseDoubleMatrix2D, etc. In general, the new matrix should have internal parametrization as similar as possible.- Returns:
- a new empty matrix of the same dynamic type.
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like
public abstract DoubleMatrix2D 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. For example, if the receiver is an instance of type DenseDoubleMatrix2D the new matrix must also be of type DenseDoubleMatrix2D, if the receiver is an instance of type SparseDoubleMatrix2D the new matrix must also be of type SparseDoubleMatrix2D, etc. In general, the new matrix should have internal parametrization as similar as possible.- 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
public abstract DoubleMatrix1D like1D(int size)
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 DenseDoubleMatrix2D the new matrix must be of type DenseDoubleMatrix1D, if the receiver is an instance of type SparseDoubleMatrix2D the new matrix must be of type SparseDoubleMatrix1D, etc.- Parameters:
size
- the number of cells the matrix shall have.- Returns:
- a new matrix of the corresponding dynamic type.
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like1D
protected abstract DoubleMatrix1D like1D(int size, int zero, int stride)
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 DenseDoubleMatrix2D the new matrix must be of type DenseDoubleMatrix1D, if the receiver is an instance of type SparseDoubleMatrix2D the new matrix must be of type SparseDoubleMatrix1D, etc.- Parameters:
size
- the number of cells the matrix shall have.zero
- 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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set
public void set(int row, int column, double value)
Sets the matrix cell at coordinate [row,column] to the specified value.- 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.- Throws:
java.lang.IndexOutOfBoundsException
- if column<0 || column>=columns() || row<0 || row>=rows()
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setQuick
public abstract void setQuick(int row, int column, double value)
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() && 0 <= row < rows().
- 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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toArray
public double[][] toArray()
Constructs and returns a 2-dimensional array containing the cell values. The returned array values has the form values[row][column] and has the same number of rows and columns as the receiver.The values are copied. So subsequent changes in values are not reflected in the matrix, and vice-versa.
- Returns:
- an array filled with the values of the cells.
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toString
public java.lang.String toString()
Returns a string representation using default formatting.- Overrides:
toString
in classjava.lang.Object
- See Also:
Formatter
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view
protected DoubleMatrix2D view()
Constructs and returns a new view equal to the receiver. The view is a shallow clone. Callsclone()
and casts the result.Note that the view is not a deep copy. The returned matrix is backed by this matrix, so changes in the returned matrix are reflected in this matrix, and vice-versa.
Use
copy()
to construct an independent deep copy rather than a new view.- Returns:
- a new view of the receiver.
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viewColumn
public DoubleMatrix1D viewColumn(int column)
Constructs and returns a new slice view representing the rows of the given column. The returned view is backed by this matrix, so changes in the returned view are reflected in this matrix, and vice-versa. To obtain a slice view on subranges, construct a sub-ranging view (viewPart(...)), then apply this method to the sub-range view.Example:
2 x 3 matrix:
1, 2, 3
4, 5, 6viewColumn(0) ==> Matrix1D of size 2:
1, 4- Parameters:
column
- the column to fix.- Returns:
- a new slice view.
- Throws:
java.lang.IndexOutOfBoundsException
- if column < 0 || column >= columns().- See Also:
viewRow(int)
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viewColumnFlip
public DoubleMatrix2D viewColumnFlip()
Constructs and returns a new flip view along the column axis. What used to be column 0 is now column columns()-1, ..., what used to be column columns()-1 is now column 0. The returned view is backed by this matrix, so changes in the returned view are reflected in this matrix, and vice-versa.Example:
2 x 3 matrix:
1, 2, 3
4, 5, 6columnFlip ==> 2 x 3 matrix:
3, 2, 1
6, 5, 4columnFlip ==> 2 x 3 matrix:
1, 2, 3
4, 5, 6- Returns:
- a new flip view.
- See Also:
viewRowFlip()
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viewDice
public DoubleMatrix2D viewDice()
Constructs and returns a new dice (transposition) view; Swaps axes; example: 3 x 4 matrix --> 4 x 3 matrix. The view has both dimensions exchanged; what used to be columns become rows, what used to be rows become columns. In other words: view.get(row,column)==this.get(column,row). This is a zero-copy transposition, taking O(1), i.e. constant time. The returned view is backed by this matrix, so changes in the returned view are reflected in this matrix, and vice-versa. Use idioms like result = viewDice(A).copy() to generate an independent transposed matrix.Example:
2 x 3 matrix:
1, 2, 3
4, 5, 6transpose ==> 3 x 2 matrix:
1, 4
2, 5
3, 6transpose ==> 2 x 3 matrix:
1, 2, 3
4, 5, 6- Returns:
- a new dice view.
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viewPart
public DoubleMatrix2D viewPart(int row, int column, int height, int width)
Constructs and returns a new sub-range view that is a height x width sub matrix starting at [row,column]. Operations on the returned view can only be applied to the restricted range. Any attempt to access coordinates not contained in the view will throw an IndexOutOfBoundsException.Note that the view is really just a range restriction: The returned matrix is backed by this matrix, so changes in the returned matrix are reflected in this matrix, and vice-versa.
The view contains the cells from [row,column] to [row+height-1,column+width-1], all inclusive. and has view.rows() == height; view.columns() == width;. A view's legal coordinates are again zero based, as usual. In other words, legal coordinates of the view range from [0,0] to [view.rows()-1==height-1,view.columns()-1==width-1]. As usual, any attempt to access a cell at a coordinate column<0 || column>=view.columns() || row<0 || row>=view.rows() will throw an IndexOutOfBoundsException.
- Parameters:
row
- The index of the row-coordinate.column
- The index of the column-coordinate.height
- The height of the box.width
- The width of the box.- Returns:
- the new view.
- Throws:
java.lang.IndexOutOfBoundsException
- if column<0 || width<0 || column+width>columns() || row<0 || height<0 || row+height>rows()
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viewRow
public DoubleMatrix1D viewRow(int row)
Constructs and returns a new slice view representing the columns of the given row. The returned view is backed by this matrix, so changes in the returned view are reflected in this matrix, and vice-versa. To obtain a slice view on subranges, construct a sub-ranging view (viewPart(...)), then apply this method to the sub-range view.Example:
2 x 3 matrix:
1, 2, 3
4, 5, 6viewRow(0) ==> Matrix1D of size 3:
1, 2, 3- Parameters:
row
- the row to fix.- Returns:
- a new slice view.
- Throws:
java.lang.IndexOutOfBoundsException
- if row < 0 || row >= rows().- See Also:
viewColumn(int)
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viewRowFlip
public DoubleMatrix2D viewRowFlip()
Constructs and returns a new flip view along the row axis. What used to be row 0 is now row rows()-1, ..., what used to be row rows()-1 is now row 0. The returned view is backed by this matrix, so changes in the returned view are reflected in this matrix, and vice-versa.Example:
2 x 3 matrix:
1, 2, 3
4, 5, 6rowFlip ==> 2 x 3 matrix:
4, 5, 6
1, 2, 3rowFlip ==> 2 x 3 matrix:
1, 2, 3
4, 5, 6- Returns:
- a new flip view.
- See Also:
viewColumnFlip()
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viewSelection
public DoubleMatrix2D viewSelection(int[] rowIndexes, int[] columnIndexes)
Constructs and returns a new selection view that is a matrix holding the indicated cells. There holds view.rows() == rowIndexes.length, view.columns() == columnIndexes.length and view.get(i,j) == this.get(rowIndexes[i],columnIndexes[j]). Indexes can occur multiple times and can be in arbitrary order.Example:
this = 2 x 3 matrix: 1, 2, 3 4, 5, 6 rowIndexes = (0,1) columnIndexes = (1,0,1,0) --> view = 2 x 4 matrix: 2, 1, 2, 1 5, 4, 5, 4
Note that modifying the index arguments after this call has returned has no effect on the view. The returned view is backed by this matrix, so changes in the returned view are reflected in this matrix, and vice-versa.To indicate "all" rows or "all columns", simply set the respective parameter
- Parameters:
rowIndexes
- The rows of the cells that shall be visible in the new view. To indicate that all rows shall be visible, simply set this parameter to null.columnIndexes
- The columns of the cells that shall be visible in the new view. To indicate that all columns shall be visible, simply set this parameter to null.- Returns:
- the new view.
- Throws:
java.lang.IndexOutOfBoundsException
- if !(0 <= rowIndexes[i] < rows()) for any i=0..rowIndexes.length()-1.java.lang.IndexOutOfBoundsException
- if !(0 <= columnIndexes[i] < columns()) for any i=0..columnIndexes.length()-1.
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viewSelection
public DoubleMatrix2D viewSelection(DoubleMatrix1DProcedure condition)
Constructs and returns a new selection view that is a matrix holding all rows matching the given condition. Applies the condition to each row and takes only those row where condition.apply(viewRow(i)) yields true. To match columns, use a dice view.Example:
// extract and view all rows which have a value < threshold in the first column (representing "age") final double threshold = 16; matrix.viewSelection( new DoubleMatrix1DProcedure() { public final boolean apply(DoubleMatrix1D m) { return m.get(0) < threshold; } } ); // extract and view all rows with RMS < threshold // The RMS (Root-Mean-Square) is a measure of the average "size" of the elements of a data sequence. matrix = 0 1 2 3 final double threshold = 0.5; matrix.viewSelection( new DoubleMatrix1DProcedure() { public final boolean apply(DoubleMatrix1D m) { return Math.sqrt(m.aggregate(F.plus,F.square) / m.size()) < threshold; } } );
For further examples, see the package doc. The returned view is backed by this matrix, so changes in the returned view are reflected in this matrix, and vice-versa.- Parameters:
condition
- The condition to be matched.- Returns:
- the new view.
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viewSelectionLike
protected abstract DoubleMatrix2D viewSelectionLike(int[] rowOffsets, int[] columnOffsets)
Construct and returns a new selection view.- Parameters:
rowOffsets
- the offsets of the visible elements.columnOffsets
- the offsets of the visible elements.- Returns:
- a new view.
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viewSorted
public DoubleMatrix2D viewSorted(int column)
Sorts the matrix rows into ascending order, according to the natural ordering of the matrix values in the given column. This sort is guaranteed to be stable. For further information, seeSorting.sort(DoubleMatrix2D,int)
. For more advanced sorting functionality, seeSorting
.- Returns:
- a new sorted vector (matrix) view.
- Throws:
java.lang.IndexOutOfBoundsException
- if column < 0 || column >= columns().
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viewStrides
public DoubleMatrix2D viewStrides(int rowStride, int columnStride)
Constructs and returns a new stride view which is a sub matrix consisting of every i-th cell. More specifically, the view has this.rows()/rowStride rows and this.columns()/columnStride columns holding cells this.get(i*rowStride,j*columnStride) for all i = 0..rows()/rowStride - 1, j = 0..columns()/columnStride - 1. The returned view is backed by this matrix, so changes in the returned view are reflected in this matrix, and vice-versa.- Parameters:
rowStride
- the row step factor.columnStride
- the column step factor.- Returns:
- a new view.
- Throws:
java.lang.IndexOutOfBoundsException
- if rowStride<=0 || columnStride<=0.
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xforEach
private boolean xforEach(DoubleProcedure procedure)
Applies a procedure to each cell's value. Iterates downwards from [rows()-1,columns()-1] to [0,0], as demonstrated by this snippet:for (int row=rows; --row >=0;) { for (int column=columns; --column >= 0;) { if (!procedure.apply(getQuick(row,column))) return false; } } return true;
Note that an implementation may use more efficient techniques, but must not use any other order.- Parameters:
procedure
- a procedure object taking as argument the current cell's value. 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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zAssign8Neighbors
public void zAssign8Neighbors(DoubleMatrix2D B, Double9Function function)
8 neighbor stencil transformation. For efficient finite difference operations. Applies a function to a moving 3 x 3 window. Does nothing if rows() < 3 || columns() < 3.B[i,j] = function.apply( A[i-1,j-1], A[i-1,j], A[i-1,j+1], A[i, j-1], A[i, j], A[i, j+1], A[i+1,j-1], A[i+1,j], A[i+1,j+1] ) x x x - - x x x - - - - x o x - - x o x - - - - x x x - - x x x ... - x x x - - - - - - - - - x o x - - - - - - - - - x x x
Make sure that cells of this and B do not overlap. In case of overlapping views, behaviour is unspecified.Example:
final double alpha = 0.25; final double beta = 0.75; // 8 neighbors cern.colt.function.Double9Function f = new cern.colt.function.Double9Function() { public final double apply( double a00, double a01, double a02, double a10, double a11, double a12, double a20, double a21, double a22) { return beta*a11 + alpha*(a00+a01+a02 + a10+a12 + a20+a21+a22); } }; A.zAssign8Neighbors(B,f); // 4 neighbors cern.colt.function.Double9Function g = new cern.colt.function.Double9Function() { public final double apply( double a00, double a01, double a02, double a10, double a11, double a12, double a20, double a21, double a22) { return beta*a11 + alpha*(a01+a10+a12+a21); } C.zAssign8Neighbors(B,g); // fast, even though it doesn't look like it };
- Parameters:
B
- the matrix to hold the results.function
- the function to be applied to the 9 cells.- Throws:
java.lang.NullPointerException
- if function==null.java.lang.IllegalArgumentException
- if rows() != B.rows() || columns() != B.columns().
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zMult
public DoubleMatrix1D zMult(DoubleMatrix1D y, DoubleMatrix1D z)
Linear algebraic matrix-vector multiplication; z = A * y; Equivalent to return A.zMult(y,z,1,0);
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zMult
public DoubleMatrix1D zMult(DoubleMatrix1D y, DoubleMatrix1D z, double alpha, double beta, boolean transposeA)
Linear algebraic matrix-vector multiplication; z = alpha * A * y + beta*z. z[i] = alpha*Sum(A[i,j] * y[j]) + beta*z[i], i=0..A.rows()-1, j=0..y.size()-1. Where A == this.
Note: Matrix shape conformance is checked after potential transpositions.- Parameters:
y
- the source vector.z
- the vector where results are to be stored. Set this parameter to null to indicate that a new result vector shall be constructed.- Returns:
- z (for convenience only).
- Throws:
java.lang.IllegalArgumentException
- if A.columns() != y.size() || A.rows() > z.size()).
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zMult
public DoubleMatrix2D zMult(DoubleMatrix2D B, DoubleMatrix2D C)
Linear algebraic matrix-matrix multiplication; C = A x B; Equivalent to A.zMult(B,C,1,0,false,false).
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zMult
public DoubleMatrix2D zMult(DoubleMatrix2D B, DoubleMatrix2D C, double alpha, double beta, boolean transposeA, boolean transposeB)
Linear algebraic matrix-matrix multiplication; C = alpha * A x B + beta*C. C[i,j] = alpha*Sum(A[i,k] * B[k,j]) + beta*C[i,j], k=0..n-1.
Matrix shapes: A(m x n), B(n x p), C(m x p).
Note: Matrix shape conformance is checked after potential transpositions.- Parameters:
B
- the second source matrix.C
- the matrix where results are to be stored. Set this parameter to null to indicate that a new result matrix shall be constructed.- Returns:
- C (for convenience only).
- Throws:
java.lang.IllegalArgumentException
- if B.rows() != A.columns().java.lang.IllegalArgumentException
- if C.rows() != A.rows() || C.columns() != B.columns().java.lang.IllegalArgumentException
- if A == C || B == C.
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zSum
public double zSum()
Returns the sum of all cells; Sum( x[i,j] ).- Returns:
- the sum.
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