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java.lang.Object cern.colt.PersistentObject cern.colt.matrix.AbstractMatrix cern.colt.matrix.AbstractMatrix2D cern.colt.matrix.tdouble.DoubleMatrix2D cern.colt.matrix.tdouble.impl.WrapperDoubleMatrix2D cern.colt.matrix.tdouble.impl.CCDoubleMatrix2D
public class CCDoubleMatrix2D
Sparse row-compressed 2-d matrix holding double elements. First see the package summary and javadoc tree view to get the broad picture.
Implementation:
Internally uses the standard sparse row-compressed format, with two important differences that broaden the applicability of this storage format:
IntArrayList
and
DoubleArrayList
to hold the column indexes and
nonzero values, respectively. This improves set(...) performance, because the
standard way of using non-resizable primitive arrays causes excessive memory
allocation, garbage collection and array copying. The small downside of this
is that set(...,0) does not free memory (The capacity of an arraylist does
not shrink upon element removal).
Memory requirements:
Cells that
trimToSize()
.
memory [bytes] = 4*rows + 12 * nonZeros.
Where nonZeros = cardinality() is the number of non-zero cells.
Thus, a 1000 x 1000 matrix with 1000000 non-zero cells consumes 11.5 MB. The
same 1000 x 1000 matrix with 1000 non-zero cells consumes 15 KB.
Time complexity:
Getting a cell value takes time O(log nzr) where nzr is the number of non-zeros of the touched row. This is usually quick, because typically there are only few nonzeros per row. So, in practice, get has expected constant time. Setting a cell value takes worst-case time O(nz) where nzr is the total number of non-zeros in the matrix. This can be extremely slow, but if you traverse coordinates properly (i.e. upwards), each write is done much quicker:
// rather quick matrix.assign(0); for (int row = 0; row < rows; row++) { for (int column = 0; column < columns; column++) { if (someCondition) matrix.setQuick(row, column, someValue); } } // poor matrix.assign(0); for (int row = rows; --row >= 0;) { for (int column = columns; --column >= 0;) { if (someCondition) matrix.setQuick(row, column, someValue); } } |
Fast iteration over non-zeros can be done via forEachNonZero(cern.colt.function.tdouble.IntIntDoubleFunction)
, which
supplies your function with row, column and value of each nonzero. Although
the internally implemented version is a bit more sophisticated, here is how a
quite efficient user-level matrix-vector multiplication could look like:
// Linear algebraic y = A * x A.forEachNonZero(new cern.colt.function.IntIntDoubleFunction() { public double apply(int row, int column, double value) { y.setQuick(row, y.getQuick(row) + value * x.getQuick(column)); return value; } }); |
Here is how a a quite efficient user-level combined scaling operation could look like:
// Elementwise A = A + alpha*B B.forEachNonZero(new cern.colt.function.IntIntDoubleFunction() { public double apply(int row, int column, double value) { A.setQuick(row, column, A.getQuick(row, column) + alpha * value); return value; } }); |
assign(DoubleMatrix2D,cern.colt.function.tdouble.DoubleDoubleFunction)
does just that if you supply
DoubleFunctions.plusMultSecond(double)
as argument.
Field Summary |
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Fields inherited from class cern.colt.PersistentObject |
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serialVersionUID |
Constructor Summary | |
---|---|
CCDoubleMatrix2D(double[][] values)
Constructs a matrix with a copy of the given values. |
|
CCDoubleMatrix2D(int rows,
int columns)
Constructs a matrix with a given number of rows and columns. |
|
CCDoubleMatrix2D(int rows,
int columns,
int nzmax)
Constructs a matrix with a given number of rows and columns. |
|
CCDoubleMatrix2D(int rows,
int columns,
int[] columnPointers,
IntArrayList rowIndexes,
DoubleArrayList values)
Constructs a matrix with indexes and values given in compressed-column format. |
|
CCDoubleMatrix2D(int rows,
int columns,
IntArrayList rowIndexes,
IntArrayList columnIndexes,
double value)
Constructs a matrix with indexes given in coordinate format and a single value. |
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CCDoubleMatrix2D(int rows,
int columns,
IntArrayList rowIndexes,
IntArrayList columnIndexes,
DoubleArrayList values)
Constructs a matrix with indexes and values given in coordinate format. |
Method Summary | |
---|---|
DoubleMatrix2D |
assign(double value)
Sets all nonzero cells to the state specified by value. |
DoubleMatrix2D |
assign(DoubleFunction function)
Assigns the result of a function to each nonzero cell; |
DoubleMatrix2D |
assign(DoubleMatrix2D source)
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 |
forEachNonZero(IntIntDoubleFunction function)
Assigns the result of a function to each non-zero cell; x[row,col] = function(x[row,col]). |
int[] |
getColumnPointers()
|
DenseDoubleMatrix2D |
getFull()
|
double |
getQuick(int row,
int column)
Returns the matrix cell value at coordinate [row,column]. |
IntArrayList |
getRowindexes()
|
DoubleArrayList |
getValues()
|
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. |
DoubleMatrix1D |
like1D(int size)
Construct and returns a new 1-d matrix of the corresponding dynamic type, entirely independent of the receiver. |
void |
setQuick(int row,
int column,
double value)
Sets the matrix cell at coordinate [row,column] to the specified value. |
void |
trimToSize()
Releases any superfluous internal memory. |
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,
double alpha,
double beta,
boolean transposeA,
boolean transposeB)
Linear algebraic matrix-matrix multiplication; C = alpha * A x B + beta*C. |
Methods inherited from class cern.colt.matrix.tdouble.impl.WrapperDoubleMatrix2D |
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elements, equals, equals, setNcolumns, setNrows, vectorize, viewColumn, viewColumnFlip, viewDice, viewPart, viewRow, viewRowFlip, viewSelection, viewStrides |
Methods inherited from class cern.colt.matrix.tdouble.DoubleMatrix2D |
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aggregate, aggregate, aggregate, aggregate, assign, assign, assign, assign, assign, assign, copy, get, getMaxLocation, getMinLocation, getNegativeValues, getNonZeros, getPositiveValues, like, normalize, set, toArray, toString, viewSelection, viewSelection, viewSorted, zAssign8Neighbors, zMult, zMult, zSum |
Methods inherited from class cern.colt.matrix.AbstractMatrix2D |
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checkShape, checkShape, columns, columnStride, index, rows, rowStride, size, toStringShort |
Methods inherited from class cern.colt.matrix.AbstractMatrix |
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ensureCapacity, isView |
Methods inherited from class cern.colt.PersistentObject |
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clone |
Methods inherited from class java.lang.Object |
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getClass, hashCode, notify, notifyAll, wait, wait, wait |
Constructor Detail |
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public CCDoubleMatrix2D(double[][] values)
The values are copied. So subsequent changes in values are not reflected in the matrix, and vice-versa.
values
- The values to be filled into the new matrix.
IllegalArgumentException
- if
for any 1 <= row < values.length: values[row].length != values[row-1].length
.public CCDoubleMatrix2D(int rows, int columns, int[] columnPointers, IntArrayList rowIndexes, DoubleArrayList values)
rows
- columns
- columnPointers
- rowIndexes
- values
- public CCDoubleMatrix2D(int rows, int columns)
rows
- the number of rows the matrix shall have.columns
- the number of columns the matrix shall have.
IllegalArgumentException
- if
rows<0 || columns<0 || (double)columns*rows > Integer.MAX_VALUE
.public CCDoubleMatrix2D(int rows, int columns, int nzmax)
rows
- the number of rows the matrix shall have.columns
- the number of columns the matrix shall have.
IllegalArgumentException
- if
rows<0 || columns<0 || (double)columns*rows > Integer.MAX_VALUE
.public CCDoubleMatrix2D(int rows, int columns, IntArrayList rowIndexes, IntArrayList columnIndexes, DoubleArrayList values)
rows
- columns
- rowIndexes
- columnIndexes
- values
- public CCDoubleMatrix2D(int rows, int columns, IntArrayList rowIndexes, IntArrayList columnIndexes, double value)
rows
- columns
- rowIndexes
- columnIndexes
- value
- Method Detail |
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public DoubleMatrix2D assign(double value)
assign
in class DoubleMatrix2D
value
- the value to be filled into the cells.
public DoubleMatrix2D assign(DoubleFunction function)
assign
in class DoubleMatrix2D
function
- a function object taking as argument the current cell's value.
DoubleFunctions
public DoubleMatrix2D assign(DoubleMatrix2D source)
assign
in class DoubleMatrix2D
source
- the source matrix to copy from (may be identical to the
receiver).
IllegalArgumentException
- if
columns() != source.columns() || rows() != source.rows()public DoubleMatrix2D assign(DoubleMatrix2D y, DoubleDoubleFunction function)
DoubleMatrix2D
Example:
// assign x[row,col] = x[row,col]<sup>y[row,col]</sup> 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 729For further examples, see the package doc.
assign
in class DoubleMatrix2D
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,
DoubleFunctions
public DoubleMatrix2D forEachNonZero(IntIntDoubleFunction function)
DoubleMatrix2D
forEachNonZero
in class DoubleMatrix2D
function
- a function object taking as argument the current non-zero
cell's row, column and value.
public IntArrayList getRowindexes()
public int[] getColumnPointers()
public DoubleArrayList getValues()
public double getQuick(int row, int 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().
getQuick
in class WrapperDoubleMatrix2D
row
- the index of the row-coordinate.column
- the index of the column-coordinate.
public DoubleMatrix2D like(int rows, int columns)
like
in class WrapperDoubleMatrix2D
rows
- the number of rows the matrix shall have.columns
- the number of columns the matrix shall have.
public DoubleMatrix1D like1D(int size)
like1D
in class WrapperDoubleMatrix2D
size
- the number of cells the matrix shall have.
public int cardinality()
DoubleMatrix2D
cardinality
in class DoubleMatrix2D
public void setQuick(int row, int column, double 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().
setQuick
in class WrapperDoubleMatrix2D
row
- the index of the row-coordinate.column
- the index of the column-coordinate.value
- the value to be filled into the specified cell.public DenseDoubleMatrix2D getFull()
public void trimToSize()
AbstractMatrix
This default implementation does nothing. Override this method if necessary.
trimToSize
in class AbstractMatrix
public DoubleMatrix1D zMult(DoubleMatrix1D y, DoubleMatrix1D z, double alpha, double beta, boolean transposeA)
DoubleMatrix2D
zMult
in class DoubleMatrix2D
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.
public DoubleMatrix2D zMult(DoubleMatrix2D B, DoubleMatrix2D C, double alpha, double beta, boolean transposeA, boolean transposeB)
DoubleMatrix2D
zMult
in class DoubleMatrix2D
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.
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Parallel Colt 0.7.2 | |||||||||
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SUMMARY: NESTED | FIELD | CONSTR | METHOD | DETAIL: FIELD | CONSTR | METHOD |