如何在Python中只替换一次regex？

Question

所以现在，re.sub会这样做：

>>> re.sub("DELETE THIS", "", "I want to DELETE THIS472 go to DON'T DELETE THIS847 the supermarket")
"I want to  go to DON'T  the supermarket"

我希望它只删除“delete THISXXX”的第一个实例，其中XXX是一个数字，因此结果是

^{pr2}$

XXX是一个变化的数字，所以我确实需要一个正则表达式。我怎样才能做到这一点？在

Answer 1

可选参数count是要替换的模式出现的最大数量；count必须是非负整数。在

re.sub(pattern, repl, string, count=0, flags=0)

将count=1设置为仅替换第一个实例。在

Answer 2

正如在re.sub(pattern, repl, string, count=0, flags=0)的documentation中所写的那样，您可以在中指定count参数：

    re.sub(pattern, repl, string[, count, flags])

如果你只给出1的计数，它只会替换第一个

Answer 3

来自http://docs.python.org/library/re#re.sub：

The optional argument count is the maximum number of pattern occurrences to be replaced; count must be a non-negative integer. If omitted or zero, all occurrences will be replaced. Empty matches for the pattern are replaced only when not adjacent to a previous match, so sub('x*', '-', 'abc') returns '-a-b-c-'.