替换但是文本中最后一次出现的字符串[重复]

2 回答

• 16

  str.replace()方法有一个 count 参数：

  str.replace（old，new [，count]）返回字符串的副本，其中所有出现的substring old都替换为new . 如果给出可选参数计数，则仅替换第一次计数 .

  然后，使用str.count()检查字符串中有多少 and 然后 -1 （因为你需要最后的 and ）：

  str.count（sub [，start [，end]]）返回[start，end]范围内substring sub的非重叠出现次数 . 可选参数start和end被解释为切片表示法 .

  演示：

  >>> string = 'Saturday and Sunday and Monday and Tuesday and Wednesday and Thursday and Friday are days of the week.'   
  >>> string.replace(' and ', ", ", (string.count(' and ')-1))
  'Saturday, Sunday, Monday, Tuesday, Wednesday, Thursday and Friday are days of the week.  '
  

  回复于 2024-04-30T13:08:37+08:00
• 4

  如果你想要一个正则表达式解决方案，你可以匹配所有 and ，后面跟着另一个字符串 .

  >>> str='Monday and Tuesday and Wednesday and Thursday and Friday and Saturday and Sunday are the days of the week.'
  >>> import re
  >>> re.sub(' and (?=.* and )', ', ', str)
  'Monday, Tuesday, Wednesday, Thursday, Friday, Saturday and Sunday are the days of the week.'
  

  (?= ... ) 是一个先行，它确保在字符串中稍后匹配，而不在实际匹配中包含它（因此也不在替换中） . 这有点像比赛的条件 .

  回复于 2024-04-30T13:08:37+08:00