/* Copyright (C) 2003 Univ. of Massachusetts Amherst, Computer Science Dept.
This file is part of "MALLET" (MAchine Learning for LanguagE Toolkit).
http://www.cs.umass.edu/~mccallum/mallet
This software is provided under the terms of the Common Public License,
version 1.0, as published by http://www.opensource.org. For further
information, see the file `LICENSE' included with this distribution. */
//package cc.mallet.util;
import java.lang.reflect.Array;
/**
* Static utility methods for arrays (like java.util.Arrays, but more useful).
*
* @author <a href="mailto:[email protected]">Charles Sutton</a>
* @version $Id: ArrayUtils.java,v 1.1 2007/10/22 21:37:40 mccallum Exp $
*/
public class Util {
/**
* Returns a new array that is the concatenation of a1 and a2.
*
* @param a1
* @param a2
* @return
*/
public static int[] append(int[] a1, int[] a2) {
int[] ret = new int[a1.length + a2.length];
System.arraycopy(a1, 0, ret, 0, a1.length);
System.arraycopy(a2, 0, ret, a1.length, a2.length);
return ret;
}
/**
* Returns a new array that is the concatenation of a1 and a2.
*
* @param a1
* @param a2
* @return
*/
public static double[] append(double[] a1, double[] a2) {
double[] ret = new double[a1.length + a2.length];
System.arraycopy(a1, 0, ret, 0, a1.length);
System.arraycopy(a2, 0, ret, a1.length, a2.length);
return ret;
}
/**
* Returns a new array with a single element appended at the end. Use this
* sparingly, for it will allocate a new array. You can easily turn a
* linear-time algorithm to quadratic this way.
*
* @param v
* Original array
* @param elem
* Element to add to end
*/
public static int[] append(int[] v, int elem) {
int[] ret = new int[v.length + 1];
System.arraycopy(v, 0, ret, 0, v.length);
ret[v.length] = elem;
return ret;
}
/**
* Returns a new array with a single element appended at the end. Use this
* sparingly, for it will allocate a new array. You can easily turn a
* linear-time algorithm to quadratic this way.
*
* @param v
* Original array
* @param elem
* Element to add to end
*/
public static boolean[] append(boolean[] v, boolean elem) {
boolean[] ret = new boolean[v.length + 1];
System.arraycopy(v, 0, ret, 0, v.length);
ret[v.length] = elem;
return ret;
}
/**
* Returns a new array with a single element appended at the end. Use this
* sparingly, for it will allocate a new array. You can easily turn a
* linear-time algorithm to quadratic this way.
*
* @param v
* Original array
* @param elem
* Element to add to end
* @return Array with length v+1 that is (v0,v1,...,vn,elem). Runtime type
* will be same as he pased-in array.
*/
public static Object[] append(Object[] v, Object elem) {
Object[] ret = (Object[]) Array.newInstance(v.getClass()
.getComponentType(), v.length + 1);
System.arraycopy(v, 0, ret, 0, v.length);
ret[v.length] = elem;
return ret;
}
}
|
|