Replace first occurrence of string in Python


Question

I have some sample string. How can I replace first occurrence of this string in a longer string with empty string?

regex = re.compile('text')
match = regex.match(url)
if match:
    url = url.replace(regex, '')
1
91
12/3/2017 3:59:14 AM

Accepted Answer

string replace() function perfectly solves this problem:

string.replace(s, old, new[, maxreplace])

Return a copy of string s with all occurrences of substring old replaced by new. If the optional argument maxreplace is given, the first maxreplace occurrences are replaced.

>>> u'longlongTESTstringTEST'.replace('TEST', '?', 1)
u'longlong?stringTEST'
199
1/29/2019 2:50:06 PM

Use re.sub directly, this allows you to specify a count:

regex.sub('', url, 1)

(Note that the order of arguments is replacement, original not the opposite, as might be suspected.)


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