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/*
* Southampton University Map App
* Copyright (C) 2011 Christopher Baines
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
package net.cbaines.suma;
import java.util.Comparator;
public class StringDistanceComparator implements Comparator<POI> {
private String userString;
// private static final String TAG = "StringDistanceComparator";
public StringDistanceComparator(String userString) {
super();
this.userString = userString;
}
public int compare(POI poi1, POI poi2) {
int distTo1 = LD(userString, poi1.toString());
// Log.i(TAG, "Comparing " + userString + " and " + poi1.toString() +
// " got dist " + distTo1);
int distTo2 = LD(userString, poi2.toString());
// Log.i(TAG, "Comparing " + userString + " and " + poi2.toString() +
// " got dist " + distTo2);
return distTo1 - distTo2;
}
// Below is public domain code from http://www.merriampark.com/ld.htm
// ****************************
// Get minimum of three values
// ****************************
private int Minimum(int a, int b, int c) {
int mi;
mi = a;
if (b < mi) {
mi = b;
}
if (c < mi) {
mi = c;
}
return mi;
}
// *****************************
// Compute Levenshtein distance
// *****************************
public int LD(String s, String t) {
int d[][]; // matrix
int n; // length of s
int m; // length of t
int i; // iterates through s
int j; // iterates through t
char s_i; // ith character of s
char t_j; // jth character of t
int cost; // cost
// Step 1
n = s.length();
m = t.length();
if (n == 0) {
return m;
}
if (m == 0) {
return n;
}
d = new int[n + 1][m + 1];
// Step 2
for (i = 0; i <= n; i++) {
d[i][0] = i;
}
for (j = 0; j <= m; j++) {
d[0][j] = j;
}
// Step 3
for (i = 1; i <= n; i++) {
s_i = s.charAt(i - 1);
// Step 4
for (j = 1; j <= m; j++) {
t_j = t.charAt(j - 1);
// Step 5
if (s_i == t_j) {
cost = 0;
} else {
cost = 1;
}
// Step 6
d[i][j] = Minimum(d[i - 1][j] + 1, d[i][j - 1] + 1, d[i - 1][j - 1] + cost);
}
}
// Step 7
return d[n][m];
}
}
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