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java.lang.Object cern.colt.PersistentObject cern.colt.matrix.AbstractMatrix cern.colt.matrix.AbstractMatrix2D cern.colt.matrix.tfloat.FloatMatrix2D cern.colt.matrix.tfloat.impl.WrapperFloatMatrix2D cern.colt.matrix.tfloat.impl.CCFloatMatrix2D
public class CCFloatMatrix2D
Sparse row-compressed 2-d matrix holding float 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
FloatArrayList
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.tfloat.IntIntFloatFunction)
, 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.IntIntFloatFunction() { public float apply(int row, int column, float 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.IntIntFloatFunction() { public float apply(int row, int column, float value) { A.setQuick(row, column, A.getQuick(row, column) + alpha * value); return value; } }); |
assign(FloatMatrix2D,cern.colt.function.tfloat.FloatFloatFunction)
does just that if you supply
FloatFunctions.plusMultSecond(float)
as argument.
Field Summary |
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Fields inherited from class cern.colt.PersistentObject |
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serialVersionUID |
Constructor Summary | |
---|---|
CCFloatMatrix2D(float[][] values)
Constructs a matrix with a copy of the given values. |
|
CCFloatMatrix2D(int rows,
int columns)
Constructs a matrix with a given number of rows and columns. |
|
CCFloatMatrix2D(int rows,
int columns,
int nzmax)
Constructs a matrix with a given number of rows and columns. |
|
CCFloatMatrix2D(int rows,
int columns,
int[] columnPointers,
IntArrayList rowIndexes,
FloatArrayList values)
Constructs a matrix with indexes and values given in compressed-column format. |
|
CCFloatMatrix2D(int rows,
int columns,
IntArrayList rowIndexes,
IntArrayList columnIndexes,
float value)
Constructs a matrix with indexes given in coordinate format and single value. |
|
CCFloatMatrix2D(int rows,
int columns,
IntArrayList rowIndexes,
IntArrayList columnIndexes,
FloatArrayList values)
Constructs a matrix with indexes and values given in coordinate format. |
Method Summary | |
---|---|
FloatMatrix2D |
assign(float value)
Sets all nonzero cells to the state specified by value. |
FloatMatrix2D |
assign(FloatFunction function)
Assigns the result of a function to each nonzero cell; |
FloatMatrix2D |
assign(FloatMatrix2D source)
Replaces all cell values of the receiver with the values of another matrix. |
FloatMatrix2D |
assign(FloatMatrix2D y,
FloatFloatFunction 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. |
FloatMatrix2D |
forEachNonZero(IntIntFloatFunction function)
Assigns the result of a function to each non-zero cell; x[row,col] = function(x[row,col]). |
int[] |
getColumnPointers()
|
DenseFloatMatrix2D |
getFull()
|
float |
getQuick(int row,
int column)
Returns the matrix cell value at coordinate [row,column]. |
IntArrayList |
getRowindexes()
|
FloatArrayList |
getValues()
|
FloatMatrix2D |
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. |
FloatMatrix1D |
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,
float value)
Sets the matrix cell at coordinate [row,column] to the specified value. |
void |
trimToSize()
Releases any superfluous internal memory. |
FloatMatrix1D |
zMult(FloatMatrix1D y,
FloatMatrix1D z,
float alpha,
float beta,
boolean transposeA)
Linear algebraic matrix-vector multiplication; z = alpha * A * y + beta*z. |
FloatMatrix2D |
zMult(FloatMatrix2D B,
FloatMatrix2D C,
float alpha,
float beta,
boolean transposeA,
boolean transposeB)
Linear algebraic matrix-matrix multiplication; C = alpha * A x B + beta*C. |
Methods inherited from class cern.colt.matrix.tfloat.impl.WrapperFloatMatrix2D |
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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.tfloat.FloatMatrix2D |
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aggregate, aggregate, aggregate, aggregate, 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 CCFloatMatrix2D(float[][] 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 CCFloatMatrix2D(int rows, int columns, int[] columnPointers, IntArrayList rowIndexes, FloatArrayList values)
rows
- columns
- columnPointers
- rowIndexes
- values
- public CCFloatMatrix2D(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 || (float)columns*rows > Integer.MAX_VALUE
.public CCFloatMatrix2D(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 || (float)columns*rows > Integer.MAX_VALUE
.public CCFloatMatrix2D(int rows, int columns, IntArrayList rowIndexes, IntArrayList columnIndexes, FloatArrayList values)
rows
- columns
- rowIndexes
- columnIndexes
- values
- public CCFloatMatrix2D(int rows, int columns, IntArrayList rowIndexes, IntArrayList columnIndexes, float value)
rows
- columns
- rowIndexes
- columnIndexes
- value
- Method Detail |
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public FloatMatrix2D assign(float value)
assign
in class FloatMatrix2D
value
- the value to be filled into the cells.
public FloatMatrix2D assign(FloatFunction function)
assign
in class FloatMatrix2D
function
- a function object taking as argument the current cell's value.
FloatFunctions
public FloatMatrix2D assign(FloatMatrix2D source)
assign
in class FloatMatrix2D
source
- the source matrix to copy from (may be identical to the
receiver).
IllegalArgumentException
- if
columns() != source.columns() || rows() != source.rows()public FloatMatrix2D assign(FloatMatrix2D y, FloatFloatFunction function)
FloatMatrix2D
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 FloatMatrix2D
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,
FloatFunctions
public FloatMatrix2D forEachNonZero(IntIntFloatFunction function)
FloatMatrix2D
forEachNonZero
in class FloatMatrix2D
function
- a function object taking as argument the current non-zero
cell's row, column and value.
public IntArrayList getRowindexes()
public int[] getColumnPointers()
public FloatArrayList getValues()
public float 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 WrapperFloatMatrix2D
row
- the index of the row-coordinate.column
- the index of the column-coordinate.
public FloatMatrix2D like(int rows, int columns)
like
in class WrapperFloatMatrix2D
rows
- the number of rows the matrix shall have.columns
- the number of columns the matrix shall have.
public FloatMatrix1D like1D(int size)
like1D
in class WrapperFloatMatrix2D
size
- the number of cells the matrix shall have.
public int cardinality()
FloatMatrix2D
cardinality
in class FloatMatrix2D
public void setQuick(int row, int column, float 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 WrapperFloatMatrix2D
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 DenseFloatMatrix2D getFull()
public void trimToSize()
AbstractMatrix
This default implementation does nothing. Override this method if necessary.
trimToSize
in class AbstractMatrix
public FloatMatrix1D zMult(FloatMatrix1D y, FloatMatrix1D z, float alpha, float beta, boolean transposeA)
FloatMatrix2D
zMult
in class FloatMatrix2D
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 FloatMatrix2D zMult(FloatMatrix2D B, FloatMatrix2D C, float alpha, float beta, boolean transposeA, boolean transposeB)
FloatMatrix2D
zMult
in class FloatMatrix2D
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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