正则表达式？匹配部分或整个单词

I was wondering if it's possible to use regex with python to capture a word, or a part of the word (if it's at the end of the string).

我想知道是否可以使用带有python的正则表达式来捕获单词或单词的一部分（如果它位于字符串的末尾）。

Eg:
target word - potato
string - "this is a sentence about a potato"
string - "this is a sentence about a potat"
string - "this is another sentence about a pota"

例如：目标词 - 马铃薯串 - “这是一个关于马铃薯的句子”字符串 - “这是一个关于potat”字符串的句子 - “这是另一个关于pota的句子”

Thanks!

谢谢！

5 个解决方案

#1

import re

def get_matcher(word, minchars):
    reg = '|'.join([word[0:i] for i in range(len(word), minchars - 1, -1)])
    return re.compile('(%s)$' % (reg))

matcher = get_matcher('potato', 4)
for s in ["this is a sentence about a potato", "this is a sentence about a potat", "this is another sentence about a pota"]:
    print matcher.search(s).groups()

OUTPUT

OUTPUT

('potato',)
('potat',)
('pota',)

#2

Dont know how to match a regex in python, but the regex would be:

不知道如何匹配python中的正则表达式，但正则表达式将是：

"\bp$|\bpo$|\bpot$|\bpota$|\bpotat$|\bpotato$"

This would match anything from p to potato if its the last word in the string, and also for example not something like "foopotato", if this is what you want.

如果它是字符串中的最后一个单词，那么这将匹配从p到马铃薯的任何东西，并且例如不是像“foopotato”这样的东西，如果这是你想要的。

The | denotes an alternative, the \b is a "word boundary", so it matches a position (not a character) between a word- and a non-word character. And the $ matches the end of the string (also a position).

|表示替代，\ b是“单词边界”，因此它匹配单词和非单词字符之间的位置（不是字符）。 $匹配字符串的结尾（也是一个位置）。

#3

Use the $ to match at the end of a string. For example, the following would match 'potato' only at the end of a string (first example):

使用$匹配字符串的末尾。例如，以下内容仅匹配字符串末尾的“马铃薯”（第一个示例）：

"potato$"

This would match all of your examples:

这将匹配您的所有示例：

"pota[to]{1,2}$"

However, some risk of also matching "potao" or "potaot".

然而，一些风险也匹配“potao”或“potaot”。

#4

import re
patt = re.compile(r'(p|po|pot|pota|potat|potato)$')
patt.search(string)

I was tempted to use r'po?t?a?t?o?$', but that would also match poto or pott.

我很想用r'po？t？a？t？o？$'，但这也会与poto或pott相匹配。

#5

No, you can't do that with a regex as far as I know, without pointless (p|po|pot ...) matches which are excessive. Instead, just pick off the last word, and match that using a substring:

不，据我所知，你不能用正则表达式做到这一点，没有毫无意义的（p | po | pot ...）匹配过多。相反，只需选择最后一个单词，然后使用子字符串匹配：

match = re.search('\S+$', haystack)
if match.group(0) == needle[:len(match.group(0))]:
    # matches.

#1

import re

def get_matcher(word, minchars):
    reg = '|'.join([word[0:i] for i in range(len(word), minchars - 1, -1)])
    return re.compile('(%s)$' % (reg))

matcher = get_matcher('potato', 4)
for s in ["this is a sentence about a potato", "this is a sentence about a potat", "this is another sentence about a pota"]:
    print matcher.search(s).groups()