pandas.Series.str.replace — pandas 2.2.3 documentation (original) (raw)

Series.str.replace(pat, repl, n=-1, case=None, flags=0, regex=False)[source]#

Replace each occurrence of pattern/regex in the Series/Index.

Equivalent to str.replace() or re.sub(), depending on the regex value.

Parameters:

patstr or compiled regex

String can be a character sequence or regular expression.

replstr or callable

Replacement string or a callable. The callable is passed the regex match object and must return a replacement string to be used. See re.sub().

nint, default -1 (all)

Number of replacements to make from start.

casebool, default None

Determines if replace is case sensitive:

• If True, case sensitive (the default if pat is a string)
• Set to False for case insensitive
• Cannot be set if pat is a compiled regex.

flagsint, default 0 (no flags)

Regex module flags, e.g. re.IGNORECASE. Cannot be set if pat is a compiled regex.

regexbool, default False

Determines if the passed-in pattern is a regular expression:

• If True, assumes the passed-in pattern is a regular expression.
• If False, treats the pattern as a literal string
• Cannot be set to False if pat is a compiled regex or repl is a callable.

Returns:

Series or Index of object

A copy of the object with all matching occurrences of pat replaced byrepl.

Raises:

ValueError

• if regex is False and repl is a callable or pat is a compiled regex
• if pat is a compiled regex and case or flags is set

Notes

When pat is a compiled regex, all flags should be included in the compiled regex. Use of case, flags, or regex=False with a compiled regex will raise an error.

Examples

When pat is a string and regex is True, the given patis compiled as a regex. When repl is a string, it replaces matching regex patterns as with re.sub(). NaN value(s) in the Series are left as is:

pd.Series(['foo', 'fuz', np.nan]).str.replace('f.', 'ba', regex=True) 0 bao 1 baz 2 NaN dtype: object

When pat is a string and regex is False, every pat is replaced withrepl as with str.replace():

pd.Series(['f.o', 'fuz', np.nan]).str.replace('f.', 'ba', regex=False) 0 bao 1 fuz 2 NaN dtype: object

When repl is a callable, it is called on every pat usingre.sub(). The callable should expect one positional argument (a regex object) and return a string.

To get the idea:

pd.Series(['foo', 'fuz', np.nan]).str.replace('f', repr, regex=True) 0 <re.Match object; span=(0, 1), match='f'>oo 1 <re.Match object; span=(0, 1), match='f'>uz 2 NaN dtype: object

Reverse every lowercase alphabetic word:

repl = lambda m: m.group(0)[::-1] ser = pd.Series(['foo 123', 'bar baz', np.nan]) ser.str.replace(r'[a-z]+', repl, regex=True) 0 oof 123 1 rab zab 2 NaN dtype: object

Using regex groups (extract second group and swap case):

pat = r"(?P\w+) (?P\w+) (?P\w+)" repl = lambda m: m.group('two').swapcase() ser = pd.Series(['One Two Three', 'Foo Bar Baz']) ser.str.replace(pat, repl, regex=True) 0 tWO 1 bAR dtype: object

Using a compiled regex with flags

import re regex_pat = re.compile(r'FUZ', flags=re.IGNORECASE) pd.Series(['foo', 'fuz', np.nan]).str.replace(regex_pat, 'bar', regex=True) 0 foo 1 bar 2 NaN dtype: object