python - 如何将 NLTK 索引结果保存在列表中？

Question

我正在使用 NLTK 在文本中查找单词。我需要将索引函数的结果保存到列表中。问题已经问了here但我看不到变化。我尝试通过以下方式查找函数返回值的类型:

type(text.concordance('myword'))

结果是:

<class 'NoneType'>

Answer 1

通过检查 ConcordanceIndex 的来源，我们可以看到结果打印到标准输出。如果redirecting stdout to a file不是一个选项，您必须重新实现 ConcordanceIndex.print_concordance 以便它返回结果而不是将其打印到标准输出。

代码:

def concordance(ci, word, width=75, lines=25):
    """
    Rewrite of nltk.text.ConcordanceIndex.print_concordance that returns results
    instead of printing them. 

    See:
    http://www.nltk.org/api/nltk.html#nltk.text.ConcordanceIndex.print_concordance
    """
    half_width = (width - len(word) - 2) // 2
    context = width // 4 # approx number of words of context

    results = []
    offsets = ci.offsets(word)
    if offsets:
        lines = min(lines, len(offsets))
        for i in offsets:
            if lines <= 0:
                break
            left = (' ' * half_width +
                    ' '.join(ci._tokens[i-context:i]))
            right = ' '.join(ci._tokens[i+1:i+context])
            left = left[-half_width:]
            right = right[:half_width]
            results.append('%s %s %s' % (left, ci._tokens[i], right))
            lines -= 1

    return results

用法:

from nltk.book import text1
from  nltk.text import ConcordanceIndex

ci = ConcordanceIndex(text1.tokens)
results = concordance(ci, 'circumstances')

print(type(results))
<class 'list'>