Skip to content

Some speed improvements #1

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Open
wants to merge 1 commit into
base: master
Choose a base branch
from
Open

Some speed improvements #1

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
1 commit
Select commit
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
7 changes: 7 additions & 0 deletions Tries/pom.xml
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,13 @@
<artifactId>fastutil</artifactId>
<version>7.1.0</version>
</dependency>
<!-- https://mvnrepository.com/artifact/com.google.guava/guava -->
<dependency>
<groupId>com.google.guava</groupId>
<artifactId>guava</artifactId>
<version>24.0-jre</version>
</dependency>

</dependencies>
<build>
<plugins>
Expand Down
40 changes: 19 additions & 21 deletions Tries/src/main/java/ug/algo/trie/Trie.java
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -1,7 +1,6 @@
package ug.algo.trie;

import java.nio.charset.Charset;
import java.util.Collections;
import java.util.HashMap;
import java.util.LinkedList;
import java.util.List;
Expand All @@ -10,6 +9,7 @@
import java.util.Vector;
import java.util.stream.Stream;

import com.google.common.primitives.Ints;
import it.unimi.dsi.fastutil.chars.Char2ObjectAVLTreeMap;

/**
Expand Down Expand Up @@ -397,16 +397,16 @@ public Map<String, Integer> getSimilarityMap(String word, int maxDistance) {
int size = word.length();

// build first row
Vector<Integer> currentRow = new Vector<Integer>(size + 1);
int[] currentRow = new int[size + 1];

for (int i = 0; i <= size; ++i) {
currentRow.insertElementAt(i, i);
currentRow[i] = i;
}

// recursively search each branch of the trie
for (Map.Entry<Character, Node> entry : root.children.entrySet()) {
results.putAll(RecursiveLevenshteinDistance(entry.getValue(), entry.getValue().getC(), word, currentRow,
results, maxDistance));
maxDistance));
}

return results;
Expand All @@ -419,34 +419,33 @@ public Map<String, Integer> getSimilarityMap(String word, int maxDistance) {
* @param letter
* @param word
* @param previousRow
* @param results
* @param maxDistance
* @return
*/
public Map<String, Integer> RecursiveLevenshteinDistance(Node node, char letter, String word,
Vector<Integer> previousRow, Map<String, Integer> results, int maxDistance) {
int[] previousRow, int maxDistance) {

//System.out.println("trie letter "+letter);
//System.out.print("previous ");
//printVector(previousRow);

int columns = previousRow.size();
Vector<Integer> currentRow = new Vector<Integer>(previousRow.size());
currentRow.add(0, previousRow.get(0) + 1);
Map<String, Integer> results = new HashMap<>();
int columns = previousRow.length;
int[] currentRow = new int[previousRow.length];
currentRow[0] = previousRow[0] + 1;
// Build one row for the letter, with a column for each letter in the
// target word, plus one for the empty string at column 0
// Calculate the min cost of insertion, deletion, match or substution
int insertCost, deleteCost, replaceCost;
for (int i = 1; i < columns; i++) {
insertCost = currentRow.get(i - 1) + 1;
deleteCost = previousRow.get(i) + 1;
insertCost = currentRow[i - 1] + 1;
deleteCost = previousRow[i] + 1;
if (word.charAt(i - 1) != letter) {
replaceCost = previousRow.get(i - 1) + 1;
replaceCost = previousRow[i - 1] + 1;
} else {
replaceCost = previousRow.get(i - 1);
replaceCost = previousRow[i - 1];
}

currentRow.add(i, Math.min(insertCost, Math.min(deleteCost, replaceCost)));
currentRow[i] = Math.min(insertCost, Math.min(deleteCost, replaceCost));
//printVector(currentRow);
}

Expand All @@ -456,7 +455,7 @@ public Map<String, Integer> RecursiveLevenshteinDistance(Node node, char letter,
// If the last entry in the row indicates the optimal cost is less than
// the maximum distance, and there is a word in this trie node, then add
// it.
if (currentRow.lastElement() <= maxDistance && node.isLeaf()) {
if (currentRow[currentRow.length - 1] <= maxDistance && node.isLeaf()) {
Node currentParent = node.getParent();
StringBuilder wordBuilder = new StringBuilder();
while (currentParent != null) {
Expand All @@ -465,17 +464,16 @@ public Map<String, Integer> RecursiveLevenshteinDistance(Node node, char letter,
}
currentParent = currentParent.getParent();
}
results.put(wordBuilder.reverse().append(node.getC()).toString(), currentRow.lastElement());
results.put(wordBuilder.reverse().append(node.getC()).toString(), currentRow[currentRow.length - 1]);
}

// If any entries in the row are less than the maximum distance, then
// recursively search each branch of the trie.
Object obj = Collections.min(currentRow);
Integer i = new Integer((int) obj);
if (i.intValue() <= maxDistance) {
int i = Ints.min(currentRow);
if (i <= maxDistance) {
for (Map.Entry<Character, Node> entry : node.children.entrySet()) {
results.putAll(RecursiveLevenshteinDistance(entry.getValue(), entry.getValue().getC(), word, currentRow,
results, maxDistance));
maxDistance));
}
}

Expand Down