N-gramme de génération à partir d'une phrase

Je crois que ce serait faire ce que vous voulez:

import java.util.*;

public class Test {

    public static List<String> ngrams(int n, String str) {
        List<String> ngrams = new ArrayList<String>();
        String[] words = str.split(" ");
        for (int i = 0; i < words.length - n + 1; i++)
            ngrams.add(concat(words, i, i+n));
        return ngrams;
    }

    public static String concat(String[] words, int start, int end) {
        StringBuilder sb = new StringBuilder();
        for (int i = start; i < end; i++)
            sb.append((i > start ? " " : "") + words[i]);
        return sb.toString();
    }

    public static void main(String[] args) {
        for (int n = 1; n <= 3; n++) {
            for (String ngram : ngrams(n, "This is my car."))
                System.out.println(ngram);
            System.out.println();
        }
    }
}

De sortie:

This
is
my
car.

This is
is my
my car.

This is my
is my car.

"À la demande" de la solution mise en œuvre comme un Itérateur:

class NgramIterator implements Iterator<String> {

    String[] words;
    int pos = 0, n;

    public NgramIterator(int n, String str) {
        this.n = n;
        words = str.split(" ");
    }

    public boolean hasNext() {
        return pos < words.length - n + 1;
    }

    public String next() {
        StringBuilder sb = new StringBuilder();
        for (int i = pos; i < pos + n; i++)
            sb.append((i > pos ? " " : "") + words[i]);
        pos++;
        return sb.toString();
    }

    public void remove() {
        throw new UnsupportedOperationException();
    }
}

OriginalL'auteur aioobe

/**
 * 
 * @param sentence should has at least one string
 * @param maxGramSize should be 1 at least
 * @return set of continuous word n-grams up to maxGramSize from the sentence
 */
public static List<String> generateNgramsUpto(String str, int maxGramSize) {

    List<String> sentence = Arrays.asList(str.split("[\\W+]"));

    List<String> ngrams = new ArrayList<String>();
    int ngramSize = 0;
    StringBuilder sb = null;

    //sentence becomes ngrams
    for (ListIterator<String> it = sentence.listIterator(); it.hasNext();) {
        String word = (String) it.next();

        //1- add the word itself
        sb = new StringBuilder(word);
        ngrams.add(word);
        ngramSize=1;
        it.previous();

        //2- insert prevs of the word and add those too
        while(it.hasPrevious() && ngramSize<maxGramSize){
            sb.insert(0,' ');
            sb.insert(0,it.previous());
            ngrams.add(sb.toString());
            ngramSize++;
        }

        //go back to initial position
        while(ngramSize>0){
            ngramSize--;
            it.next();
        }                   
    }
    return ngrams;
}

Appel:

long startTime = System.currentTimeMillis();
ngrams = ToolSet.generateNgramsUpto("This is my car.", 3);
long stopTime = System.currentTimeMillis();
System.out.println("My time = "+(stopTime-startTime)+" ms with ngramsize = "+ngrams.size());
System.out.println(ngrams.toString());

De sortie:

Mon temps = 1 ms avec ngramsize = 9 [Ce, qui est, C'est, mon, mon, Ce
est mon, voiture, ma voiture, ma voiture est]

OriginalL'auteur tozCSS

public static void main(String[] args) {
String[] words = "This is my car.".split(" ");
for (int n = 0; n < 3; n++) {
List<String> list = ngrams(n, words);
for (String ngram : list) {
System.out.println(ngram);
}
System.out.println();
}
}
public static List<String> ngrams(int stepSize, String[] words) {
List<String> ngrams = new ArrayList<String>();
for (int i = 0; i < words.length-stepSize; i++) {
String initialWord = "";
int internalCount = i;
int internalStepSize = i + stepSize;
while (internalCount <= internalStepSize
&& internalCount < words.length) {
initialWord = initialWord+" " + words[internalCount];
++internalCount;
}
ngrams.add(initialWord);
}
return ngrams;
}

OriginalL'auteur M Sach