python之nltk 的新手，条件频率有问题

我是 python 和 nltk 的新手(我 2 小时前开始)。这是我被要求做的事情:

Write a function GetAmbigousWords(corpus, N) that finds words in the corpus with more than N observed tags. This function should return a ConditionalFreqDist object where the conditions are the words and the frequency distribution indicates the tag frequencies for each word.

这是我到目前为止所做的:

def GetAmbiguousWords(corpus, number): 
conditional_frequency = ConditionalFreqDist() 
word_tag_dict = defaultdict(set)       # Creates a dictionary of sets 
for (word, tag) in corpus: 
    word_tag_dict[word].add(tag) 
 
for taggedWord in word_tag_dict: 
    if ( len(word_tag_dict[taggedWord]) >= number ): 
        condition = taggedWord 
        conditional_frequency[condition] # do something, I don't know what to do 
 
return conditional_frequency 

例如以下是该函数的行为方式:

GetAmbiguousWords(nltk.corpus.brown.tagged_words(categories='news'), 4) 

我想知道我是在正确的轨道上还是完全偏离了轨道？特别是我不是很懂conditional frequency .

提前致谢。

请您参考如下方法:

通过频率分布，您可以收集一个词在文本中出现的频率:

text = "cow cat mouse cat tiger" 
 
fDist = FreqDist(word_tokenize(text)) 
 
for word in fDist: 
    print "Frequency of", word, fDist.freq(word) 

这将导致:

Frequency of tiger 0.2 
Frequency of mouse 0.2 
Frequency of cow 0.2 
Frequency of cat 0.4 

现在，条件频率基本相同，但您添加了一个条件，您可以根据该条件对频率进行分组。例如。按字长分组:

cfdist = ConditionalFreqDist() 
 
for word in word_tokenize(text): 
    condition = len(word) 
    cfdist[condition][word] += 1 
 
for condition in cfdist: 
    for word in cfdist[condition]: 
        print "Cond. frequency of", word, cfdist[condition].freq(word), "[condition is word length =", condition, "]" 

这将打印:

Cond. frequency of cow 0.333333333333 [condition is word length = 3 ] 
Cond. frequency of cat 0.666666666667 [condition is word length = 3 ] 
Cond. frequency of tiger 0.5 [condition is word length = 5 ] 
Cond. frequency of mouse 0.5 [condition is word length = 5 ] 

希望对您有所帮助。