如何替换文本中的字符串列表，其中一些字符串是python中其他字符串的子串？

Question

I have a text containing some words that I would like to tag, and the words to be tagged are contained in a List. The problem is that some of those words are substrings of others, but I want to tag the longest recognized string from the list.

For example, if my text is "foo and bar are different from foo bar." and my list contains "foo", "bar" and "foo bar" the result should be "[tag]foo[/tag] and [tag]bar[/tag] are different from [tag]foo bar[/tag]."

text = "foo and bar are different from foo bar."
words = ["foo", "bar", "foo bar"]

tagged = someFunction(text, words)

What should be the code of someFunction in such a way that the value of the string taggedText is "<tag>foo</tag> and <tag>bar</tag> are different from <tag>foo bar</tag>." ?

Answer 1

If I understood your problem correctly, then this is something you are looking for :-

text = "foo and bar are different from foo bar."
words = ["foo", "bar", "foo bar"]

add_tag = lambda var : "<tag>"+var+"</tag>"

result = ''    # for final string
for var in text.split():
    if var in words:
        tmp = add_tag(var)
    else:
        tmp = var
    result += " "+tmp

print result    
return result

Here add_tag() method is serving what you are looking in someFunction .

Answer 2

A simple way to achieve that would be to sort words by length in the reversed order and then create a regular expression word1|word2|... . Since the re engine always takes the first match, longer strings will be catched first.

import re

def tag_it(text, words):
    return re.sub(
            '|'.join(sorted(words, key=len, reverse=True)),
            lambda m: '<tag>' + m.group(0) + '</tag>',
            text)


text = "foo and bar are different from foo bar."
words = ["foo", "bar", "foo bar"]


print tag_it(text, words)