在python中使用相关视图查找关键字

Question

def concordance(string, search_term, width=80):
    offset = 0
    indexes = []

  while offset < len(string):
    try:

        position = string[offset:].lower().index(search_term.lower())
    except ValueError:

        break
    if position:
        indexes.append(position + offset)

        offset += position + len(search_term)
   return tuple(string[index-width:index+width+len(search_term)] 

string = 'The relationship between beef and beef broth, is not like the 
relationship between beef and beef-broth, a simpler extraction and 
condensation; rather, as Einstein goes on, it is like the relationship 
between our overcoat and the ticket given us when we check our overcoat. In 
other words, human perception involves coding even more than crude 
sensing.just as a map-maker colors a nation purple not because it is purple 
but because his code demands it."  

当我尝试在search_term为‘and’的情况下调用concordance函数时，结果不仅返回'and'，而且还返回其中包含and的单词，如'demand‘。我如何修改我的代码，使其只返回'and'？

Answer 1

正如评论中提到的:您可以尝试使用re module。在这里，我尝试匹配您的search_term，仅当它被不在[a-zA-Z0-9_]中的字符包围时(不确定这是否最适合您的意图...)：

import re

def concordance(strg, search_term, width=5):
    ret = []
    # \W Matches any character which is not a word character. 
    # ~ anything that is not [a-zA-Z0-9_]
    rgx = re.compile('\W{}\W'.format(search_term))
    match_end = 0
    while True:
        match = rgx.search(strg, match_end)
        if match is None:
            break
        ret.append(strg[match.start()+1-width:match.end()-1+width])
        match_end = match.end()
    return ret


print(concordance(strg, 'and'))  
# ['beef and beef', 'beef and beef', 'tion and\ncond', 'coat and the ']