双分法行为错误

Question

我有一个HashMap叫List<String, Intger> wordFreqMap其sizeIS234

wordFreqMap = {radiology=1, shift=2, mummy=1, empirical=1, awful=1, geoff=1, .......}

我想计算term frequency每个单词的。

term frequency = frequency of term / total number of terms

public static Map<String, Double> getTFMap (Map<String, Integer> wordFreqMap)
    {
        Map<String, Double> tfMap = new HashMap<String, Double>();
        int noOfTerms = wordFreqMap.size();
        Double tf;

        for (Entry<String, Integer> word : wordFreqMap.entrySet() ) 
        {
                tf = (double) ( word.getValue() / noOfTerms );
                tfMap.put(word.getKey(), tf );
        }
        return tfMap;
    }

我的问题是，tfMap返回{radiology=0.0, shift=0.0, mummy=0.0, empirical=0.0, awful=0.0, geoff=0.0, .....}

我不明白为什么0.0每学期都会回来。我如何解决它？

我应该得到类似 {radiology=0.00427, shift=0.00854, ...}

Answer 1

您正在执行整数除法，然后键入强制转换：

tf = (double) ( word.getValue() / noOfTerms );
                ^-----integer division----^

类型转换将除法中的元素之一转换为浮点除法：

tf = ((double)word.getValue()) / noOfTerms;