java weka stringtowordvector is not counting word

问题:

so I'm using Weka Machine Learning Library's JAVA API and I have the following code:

    String html = "repeat repeat repeat";

    Attribute input = new Attribute("html",(FastVector) null);

    FastVector inputVec = new FastVector();
    inputVec.addElement(input);

    Instances htmlInst = new Instances("html",inputVec,1);
    htmlInst.add(new Instance(1));  
    htmlInst.instance(0).setValue(0, html);

    StringToWordVector filter = new StringToWordVector();
    filter.setUseStoplist(true);

    filter.setInputFormat(htmlInst);
    Instances dataFiltered = Filter.useFilter(htmlInst, filter);

    Instance last = dataFiltered.lastInstance();
    System.out.println(last);

though StringToWordVector is supposed to count the word occurences within the string, instead of having the word 'repeat' counted 3 times, the count only comes out as 1

what am I doing wrong?

回答1:

Gee... all those lines of code. How about these few lines instead?

public static Map<String, Integer> countWords(String input) {
    Map<String, Integer> map = new HashMap<String, Integer>();
    Matcher matcher = Pattern.compile("\\b\\w+\\b").matcher(input);
    while (matcher.find())
        map.put(matcher.group(), map.containsKey(matcher.group()) ? map.get(matcher.group()) + 1 : 1);
    return map;
}

Here's the code in action:

public static void main(String[] args) {
    System.out.println(countWords("sample, repeat sample, of text"));
}

Output:

{of=1, text=1, repeat=1, sample=2}

回答2:

The default setting is only reporting presence/absence as 0/1. You must enable counting explicitly. Add:

filter.setOutputWordCounts(true);

and re-run.

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