Re: How to check variables for uniqueness ?

Lew skrev:


snip


Indeed.

And in case anyone's interested, here are the times for HashMap. Looks
like Map is in the league of Set, and not the slow-moving List. (These
times are longer than the previous times because of current CPU
loading; relativity is the key.)

522393 duplicated words. Using java.util.HashSet, time = 789ms.
522393 duplicated words. Using java.util.TreeSet, time = 2168ms.
522393 duplicated words. Using Map , time = 1180ms.
522393 duplicated words. Using java.util.ArrayList, time = 183795ms.
522393 duplicated words. Using java.util.LinkedList, time = 274781ms.

Apologies to Patricia: I see I mis-attributed her post, yet again. And
Lew, I've now become fast friends now with Linux's expand(). Let's see
whether I purged those nasty TABs:

import java.util.*;
import java.io.*;

class Test {
    private static String TEXT_BOOK_NAME = "war-and-peace.txt";

    public static void main(String[] args) {
    try {
        String text = readText(); // Read text into RAM
        countDuplicateWords(text, new HashSet());
        countDuplicateWords(text, new TreeSet());
        countDuplicateWordsMap(text);
        countDuplicateWords(text, new ArrayList());
        countDuplicateWords(text, new LinkedList());
    } catch (Throwable t) {
        System.out.println(t.toString());
    }
    }

    private static String readText() throws Throwable {
    BufferedReader reader =
        new BufferedReader(new FileReader(TEXT_BOOK_NAME));
    String line = null;
    StringBuffer text = new StringBuffer();
    while ((line = reader.readLine()) != null) {
        text.append(line + " ");
    }
    return text.toString();
    }

    private static void countDuplicateWords(String text,
                        Collection listOfWords) {
    int numDuplicatedWords = 0;
    long startTime = System.currentTimeMillis();
    for (StringTokenizer i = new StringTokenizer(text);
         i.hasMoreElements();) {
        String word = i.nextToken();
        if (listOfWords.contains(word)) {
        numDuplicatedWords++;
        } else {
        listOfWords.add(word);
        }
    }
    long endTime = System.currentTimeMillis();
    System.out.println(numDuplicatedWords + " duplicated words. " +
               "Using " + listOfWords.getClass().getName() +
               ", time = " + (endTime - startTime) + "ms.");
    }

    private static void countDuplicateWordsMap(String text) {
    int numDuplicatedWords = 0;
    Map wordsToFrequency = new HashMap();
    long startTime = System.currentTimeMillis();
    for (StringTokenizer i = new StringTokenizer(text);
         i.hasMoreElements();) {
        String word = i.nextToken();
        Integer frequency = (Integer)wordsToFrequency.get(word);
        if (frequency == null) {
        wordsToFrequency.put(word, new Integer(0));
        } else {
        int value = frequency.intValue();
        wordsToFrequency.put(word, new Integer(value + 1));
        numDuplicatedWords++;
        }
    }
    long endTime = System.currentTimeMillis();
    System.out.println(numDuplicatedWords + " duplicated words. " +
               "Using Map " +
               ", time = " + (endTime - startTime) + "ms.");
    }
}

..ed

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