Question

假设我有以下句子：

bean likes to sell his beans

我希望用其他单词替换所有出现的特定单词。例如，bean到robert和beans到cars。

我不能只使用str.replace，因为在这种情况下，它会将beans更改为roberts。

>>> "bean likes to sell his beans".replace("bean","robert")
'robert likes to sell his roberts'

我只需改变整个单词，而不是另一个单词中出现的单词。我认为我可以通过使用正则表达式实现这一点，但不知道如何正确执行。

Answer 1

如果您使用正则表达式，则可以使用\b指定字边界：

import re

sentence = 'bean likes to sell his beans'

sentence = re.sub(r'\bbean\b', 'robert', sentence)
# 'robert likes to sell his beans'

这里＆＃39;豆类＆＃39;不会改变（因为＆＃39; roberts＆＃39;）因为＆＃39; s＆＃39;最后不是单词之间的边界：\b匹配空字符串，但仅在单词的开头或结尾。

完成性的第二次替换：

sentence = re.sub(r'\bbeans\b', 'cars', sentence)
# 'robert likes to sell his cars'

Answer 2

如果您一次更换一个单词，您可能会多次替换单词（而不是得到您想要的单词）。为避免这种情况，您可以使用函数或lambda：

d = {'bean':'robert', 'beans':'cars'}
str_in = 'bean likes to sell his beans'
str_out = re.sub(r'\b(\w+)\b', lambda m:d.get(m.group(1), m.group(1)), str_in)

这样，一旦bean被robert替换，就不会再次修改（即使robert也在您的输入词汇列表中）。

根据 georg 的建议，我使用dict.get(key, default_value)编辑了此答案。替代解决方案（也由 georg 建议）：

str_out = re.sub(r'\b(%s)\b' % '|'.join(d.keys()), lambda m:d.get(m.group(1), m.group(1)), str_in)

Answer 3

"bean likes to sell his beans".replace("beans", "cars").replace("bean", "robert")

将所有“beans”实例替换为“car”，将“bean”替换为“robert”。这是有效的，因为.replace()返回原始字符串的修改实例。因此，您可以分阶段思考它。它基本上是这样工作的：

 >>> first_string = "bean likes to sell his beans"
 >>> second_string = first_string.replace("beans", "cars")
 >>> third_string = second_string.replace("bean", "robert")
 >>> print(first_string, second_string, third_string)

 ('bean likes to sell his beans', 'bean likes to sell his cars', 
  'robert likes to sell his cars')

Answer 4

我知道它已经很长时间了，但这看起来更优雅吗？：

reduce(lambda x,y : re.sub('\\b('+y[0]+')\\b',y[1],x) ,[("bean","robert"),("beans","cars")],"bean likes to sell his beans")

替换所有特定单词的出现

4 个答案: