Parallel Colt 0.7.2

cern.colt.matrix.tint.impl
Class RCIntMatrix2D

java.lang.Object
  extended by cern.colt.PersistentObject
      extended by cern.colt.matrix.AbstractMatrix
          extended by cern.colt.matrix.AbstractMatrix2D
              extended by cern.colt.matrix.tint.IntMatrix2D
                  extended by cern.colt.matrix.tint.impl.WrapperIntMatrix2D
                      extended by cern.colt.matrix.tint.impl.RCIntMatrix2D
All Implemented Interfaces:
Serializable, Cloneable

public class RCIntMatrix2D
extends WrapperIntMatrix2D

Sparse row-compressed 2-d matrix holding int 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:


Note that this implementation is not synchronized.

Memory requirements:

Cells that

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);
     }
 }
 
If for whatever reasons you can't iterate properly, consider to create an empty dense matrix, store your non-zeros in it, then call sparse.assign(dense). Under the circumstances, this is still rather quick.

Fast iteration over non-zeros can be done via forEachNonZero(cern.colt.function.tint.IntIntIntFunction), 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.IntIntIntFunction() {
     public int apply(int row, int column, int 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.IntIntIntFunction() {
     public int apply(int row, int column, int value) {
         A.setQuick(row, column, A.getQuick(row, column) + alpha * value);
         return value;
     }
 });
 
Method assign(IntMatrix2D,cern.colt.function.tint.IntIntFunction) does just that if you supply IntFunctions.plusMultSecond(int) as argument.

Version:
0.9, 04/14/2000
Author:
wolfgang.hoschek@cern.ch
See Also:
Serialized Form

Field Summary
 
Fields inherited from class cern.colt.PersistentObject
serialVersionUID
 
Constructor Summary
RCIntMatrix2D(int[][] values)
          Constructs a matrix with a copy of the given values.
RCIntMatrix2D(int rows, int columns)
          Constructs a matrix with a given number of rows and columns.
RCIntMatrix2D(int rows, int columns, int nzmax)
          Constructs a matrix with a given number of rows and columns.
RCIntMatrix2D(int rows, int columns, int[] rowPointers, IntArrayList columnIndexes, IntArrayList values)
           
 
Method Summary
 IntMatrix2D assign(int value)
          Sets all nonzero cells to the state specified by value.
 IntMatrix2D assign(IntFunction function)
          Assigns the result of a function to each nonzero cell;
 IntMatrix2D assign(IntMatrix2D source)
          Replaces all cell values of the receiver with the values of another matrix.
 IntMatrix2D assign(IntMatrix2D y, IntIntFunction 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.
 IntMatrix2D forEachNonZero(IntIntIntFunction function)
          Assigns the result of a function to each non-zero cell; x[row,col] = function(x[row,col]).
 IntArrayList getColumnindexes()
           
 DenseIntMatrix2D getFull()
           
 int getQuick(int row, int column)
          Returns the matrix cell value at coordinate [row,column].
 int[] getRowPointers()
           
 IntArrayList getValues()
           
 IntMatrix2D 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.
 IntMatrix1D 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, int value)
          Sets the matrix cell at coordinate [row,column] to the specified value.
 void trimToSize()
          Releases any superfluous internal memory.
 IntMatrix1D zMult(IntMatrix1D y, IntMatrix1D z)
          Linear algebraic matrix-vector multiplication; z = A * y; Equivalent to return A.zMult(y,z,1,0);
 IntMatrix1D zMult(IntMatrix1D y, IntMatrix1D z, int alpha, int beta, boolean transposeA)
          Linear algebraic matrix-vector multiplication; z = alpha * A * y + beta*z.
 IntMatrix2D zMult(IntMatrix2D B, IntMatrix2D C)
          Linear algebraic matrix-matrix multiplication; C = A x B; Equivalent to A.zMult(B,C,1,0,false,false).
 IntMatrix2D zMult(IntMatrix2D B, IntMatrix2D C, int alpha, int beta, boolean transposeA, boolean transposeB)
          Linear algebraic matrix-matrix multiplication; C = alpha * A x B + beta*C.
 
Methods inherited from class cern.colt.matrix.tint.impl.WrapperIntMatrix2D
elements, setNcolumns, setNrows, vectorize, viewColumn, viewColumnFlip, viewDice, viewPart, viewRow, viewRowFlip, viewSelection, viewStrides
 
Methods inherited from class cern.colt.matrix.tint.IntMatrix2D
aggregate, aggregate, aggregate, aggregate, assign, assign, assign, assign, assign, copy, equals, equals, get, getMaxLocation, getMinLocation, getNegativeValues, getNonZeros, getPositiveValues, like, set, toArray, toString, viewSelection, viewSelection, viewSorted, zSum
 
Methods inherited from class cern.colt.matrix.AbstractMatrix2D
checkShape, checkShape, columns, columnStride, index, rows, rowStride, size, toStringShort
 
Methods inherited from class cern.colt.matrix.AbstractMatrix
ensureCapacity, isView
 
Methods inherited from class cern.colt.PersistentObject
clone
 
Methods inherited from class java.lang.Object
getClass, hashCode, notify, notifyAll, wait, wait, wait
 

Constructor Detail

RCIntMatrix2D

public RCIntMatrix2D(int[][] values)
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 .

RCIntMatrix2D

public RCIntMatrix2D(int rows,
                     int columns,
                     int[] rowPointers,
                     IntArrayList columnIndexes,
                     IntArrayList values)

RCIntMatrix2D

public RCIntMatrix2D(int rows,
                     int columns)
Constructs a matrix with a given number of rows and columns. All entries are initially 0.

Parameters:
rows - the number of rows the matrix shall have.
columns - the number of columns the matrix shall have.
Throws:
IllegalArgumentException - if rows<0 || columns<0 || (int)columns*rows > Integer.MAX_VALUE .

RCIntMatrix2D

public RCIntMatrix2D(int rows,
                     int columns,
                     int nzmax)
Constructs a matrix with a given number of rows and columns. All entries are initially 0.

Parameters:
rows - the number of rows the matrix shall have.
columns - the number of columns the matrix shall have.
Throws:
IllegalArgumentException - if rows<0 || columns<0 || (int)columns*rows > Integer.MAX_VALUE .
Method Detail

assign

public IntMatrix2D assign(int value)
Sets all nonzero cells to the state specified by value.

Overrides:
assign in class IntMatrix2D
Parameters:
value - the value to be filled into the cells.
Returns:
this (for convenience only).

assign

public IntMatrix2D assign(IntFunction function)
Assigns the result of a function to each nonzero cell;

Overrides:
assign in class IntMatrix2D
Parameters:
function - a function object taking as argument the current cell's value.
Returns:
this (for convenience only).
See Also:
IntFunctions

assign

public IntMatrix2D assign(IntMatrix2D source)
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.

Overrides:
assign in class IntMatrix2D
Parameters:
source - the source matrix to copy from (may be identical to the receiver).
Returns:
this (for convenience only).
Throws:
IllegalArgumentException - if columns() != source.columns() || rows() != source.rows()

assign

public IntMatrix2D assign(IntMatrix2D y,
                          IntIntFunction function)
Description copied from class: IntMatrix2D
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]<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 
   16 729
 
 
For further examples, see the package doc.

Overrides:
assign in class IntMatrix2D
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).
See Also:
IntFunctions

forEachNonZero

public IntMatrix2D forEachNonZero(IntIntIntFunction function)
Description copied from class: IntMatrix2D
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.

Overrides:
forEachNonZero in class IntMatrix2D
Parameters:
function - a function object taking as argument the current non-zero cell's row, column and value.
Returns:
this (for convenience only).

getColumnindexes

public IntArrayList getColumnindexes()

getRowPointers

public int[] getRowPointers()

getValues

public IntArrayList getValues()

getQuick

public int 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().

Overrides:
getQuick in class WrapperIntMatrix2D
Parameters:
row - the index of the row-coordinate.
column - the index of the column-coordinate.
Returns:
the value at the specified coordinate.

like

public IntMatrix2D 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 DenseIntMatrix2D the new matrix must also be of type DenseIntMatrix2D, if the receiver is an instance of type SparseIntMatrix2D the new matrix must also be of type SparseIntMatrix2D, etc. In general, the new matrix should have internal parametrization as similar as possible.

Overrides:
like in class WrapperIntMatrix2D
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.

like1D

public IntMatrix1D like1D(int size)
Construct and returns a new 1-d matrix of the corresponding dynamic type, entirely independent of the receiver. For example, if the receiver is an instance of type DenseIntMatrix2D the new matrix must be of type DenseIntMatrix1D, if the receiver is an instance of type SparseIntMatrix2D the new matrix must be of type SparseIntMatrix1D, etc.

Overrides:
like1D in class WrapperIntMatrix2D
Parameters:
size - the number of cells the matrix shall have.
Returns:
a new matrix of the corresponding dynamic type.

cardinality

public int cardinality()
Description copied from class: IntMatrix2D
Returns the number of cells having non-zero values; ignores tolerance.

Overrides:
cardinality in class IntMatrix2D
Returns:
cardinality

setQuick

public void setQuick(int row,
                     int column,
                     int 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().

Overrides:
setQuick in class WrapperIntMatrix2D
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.

getFull

public DenseIntMatrix2D getFull()

trimToSize

public void trimToSize()
Description copied from class: AbstractMatrix
Releases any superfluous internal memory. An application can use this operation to minimize the storage of the receiver.

This default implementation does nothing. Override this method if necessary.

Overrides:
trimToSize in class AbstractMatrix

zMult

public IntMatrix1D zMult(IntMatrix1D y,
                         IntMatrix1D z)
Description copied from class: IntMatrix2D
Linear algebraic matrix-vector multiplication; z = A * y; Equivalent to return A.zMult(y,z,1,0);

Overrides:
zMult in class IntMatrix2D

zMult

public IntMatrix1D zMult(IntMatrix1D y,
                         IntMatrix1D z,
                         int alpha,
                         int beta,
                         boolean transposeA)
Description copied from class: IntMatrix2D
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.

Overrides:
zMult in class IntMatrix2D
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).

zMult

public IntMatrix2D zMult(IntMatrix2D B,
                         IntMatrix2D C)
Description copied from class: IntMatrix2D
Linear algebraic matrix-matrix multiplication; C = A x B; Equivalent to A.zMult(B,C,1,0,false,false).

Overrides:
zMult in class IntMatrix2D

zMult

public IntMatrix2D zMult(IntMatrix2D B,
                         IntMatrix2D C,
                         int alpha,
                         int beta,
                         boolean transposeA,
                         boolean transposeB)
Description copied from class: IntMatrix2D
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.

Overrides:
zMult in class IntMatrix2D
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).

Parallel Colt 0.7.2

Jump to the Parallel Colt Homepage