smile.util

Class IntArray2D

java.lang.Object

smile.util.IntArray2D

public class IntArray2D
extends java.lang.Object

2-dimensional array of integers. Java doesn't have real multidimensional arrays. They are just array of arrays, which are not friendly to modern CPU due to frequent cache miss. The extra (multiple times) array index checking also significantly reduces the performance. This class solves these pain points by storing data in a single 1D array of int in row major order. Note that this class is simple by design, as a replacement of int[][] in case of row by row access. For advanced matrix computation, please use Matrix.

See Also:

Matrix

Constructor Summary

Constructors

Constructor and Description
IntArray2D(int[][] A) Constructor.
IntArray2D(int rows, int cols) Constructor of all-zero matrix.
IntArray2D(int rows, int cols, int value) Constructor.
IntArray2D(int rows, int cols, int[] value) Constructor.

Method Summary

Modifier and Type	Method and Description
IntArray2D	add(int x)
IntArray2D	add(IntArray2D b)
int	add(int i, int j, int x)
int	apply(int i, int j) Returns A(i, j).
IntArray2D	div(int x)
IntArray2D	div(IntArray2D b)
int	div(int i, int j, int x)
int	get(int i, int j) Returns A(i, j).
IntArray2D	mul(int x)
IntArray2D	mul(IntArray2D b)
int	mul(int i, int j, int x)
int	ncols()
int	nrows()
int	set(int i, int j, int x) Sets A(i, j).
IntArray2D	sub(int x)
IntArray2D	sub(IntArray2D b)
int	sub(int i, int j, int x)
long	sum()
java.lang.String	toString()
java.lang.String	toString(boolean full) Returns the string representation of matrix.
java.lang.String	toString(int m, int n) Returns the string representation of matrix.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Constructor Detail

IntArray2D

public IntArray2D(int[][] A)

Constructor.

Parameters:

A - the array of matrix.

IntArray2D

public IntArray2D(int rows,
                  int cols)

Constructor of all-zero matrix.

IntArray2D

public IntArray2D(int rows,
                  int cols,
                  int value)

Constructor. Fill the matrix with given value.

IntArray2D

public IntArray2D(int rows,
                  int cols,
                  int[] value)

Constructor.

Parameters:

value - the array of matrix values arranged in row major format

Method Detail

nrows

public int nrows()

ncols

public int ncols()

apply

public int apply(int i,
                 int j)

Returns A(i, j). Useful in Scala.

get

public int get(int i,
               int j)

Returns A(i, j).

set

public int set(int i,
               int j,
               int x)

Sets A(i, j).

add

public int add(int i,
               int j,
               int x)

sub

public int sub(int i,
               int j,
               int x)

mul

public int mul(int i,
               int j,
               int x)

div

public int div(int i,
               int j,
               int x)

add

public IntArray2D add(IntArray2D b)

sub

public IntArray2D sub(IntArray2D b)

mul

public IntArray2D mul(IntArray2D b)

div

public IntArray2D div(IntArray2D b)

add

public IntArray2D add(int x)

sub

public IntArray2D sub(int x)

mul

public IntArray2D mul(int x)

div

public IntArray2D div(int x)

sum

public long sum()

toString

public java.lang.String toString()

Overrides:

toString in class java.lang.Object

toString

public java.lang.String toString(boolean full)

Returns the string representation of matrix.

Parameters:

full - Print the full matrix if true. Otherwise, print only top left 7 x 7 submatrix.

toString

public java.lang.String toString(int m,
                                 int n)

Returns the string representation of matrix.

Parameters:

m - the number of rows to print.

n - the number of columns to print.