pandas.Series.str.split#

Series.str.split(pat=None, *, n=-1, expand=False, regex=None)[source]#

Split strings around given separator/delimiter.

Splits the string in the Series/Index from the beginning, at the specified delimiter string.

Parameters:
patstr or compiled regex, optional

String or regular expression to split on. If not specified, split on whitespace.

nint, default -1 (all)

Limit number of splits in output. None, 0 and -1 will be interpreted as return all splits.

expandbool, default False

Expand the split strings into separate columns.

  • If True, return DataFrame/MultiIndex expanding dimensionality.

  • If False, return Series/Index, containing lists of strings.

regexbool, default None

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.

  • If None and pat length is 1, treats pat as a literal string.

  • If None and pat length is not 1, treats pat as a regular expression.

  • Cannot be set to False if pat is a compiled regex

New in version 1.4.0.

Returns:
Series, Index, DataFrame or MultiIndex

Type matches caller unless expand=True (see Notes).

Raises:
ValueError

  • if regex is False and pat is a compiled regex

See also

Series.str.split

Split strings around given separator/delimiter.

Series.str.rsplit

Splits string around given separator/delimiter, starting from the right.

Series.str.join

Join lists contained as elements in the Series/Index with passed delimiter.

str.split

Standard library version for split.

str.rsplit

Standard library version for rsplit.

Notes

The handling of the n keyword depends on the number of found splits:

  • If found splits > n, make first n splits only

  • If found splits <= n, make all splits

  • If for a certain row the number of found splits < n, append None for padding up to n if expand=True

If using expand=True, Series and Index callers return DataFrame and MultiIndex objects, respectively.

Use of regex =False with a pat as a compiled regex will raise an error.

Examples

>>> s = pd.Series(
...     [
...         "this is a regular sentence",
...         "https://docs.python.org/3/tutorial/index.html",
...         np.nan
...     ]
... )
>>> s
0                       this is a regular sentence
1    https://docs.python.org/3/tutorial/index.html
2                                              NaN
dtype: object

In the default setting, the string is split by whitespace.

>>> s.str.split()
0                   [this, is, a, regular, sentence]
1    [https://docs.python.org/3/tutorial/index.html]
2                                                NaN
dtype: object

Without the n parameter, the outputs of rsplit and split are identical.

>>> s.str.rsplit()
0                   [this, is, a, regular, sentence]
1    [https://docs.python.org/3/tutorial/index.html]
2                                                NaN
dtype: object

The n parameter can be used to limit the number of splits on the delimiter. The outputs of split and rsplit are different.

>>> s.str.split(n=2)
0                     [this, is, a regular sentence]
1    [https://docs.python.org/3/tutorial/index.html]
2                                                NaN
dtype: object

>>> s.str.rsplit(n=2)
0                     [this is a, regular, sentence]
1    [https://docs.python.org/3/tutorial/index.html]
2                                                NaN
dtype: object

The pat parameter can be used to split by other characters.

>>> s.str.split(pat="/")
0                         [this is a regular sentence]
1    [https:, , docs.python.org, 3, tutorial, index...
2                                                  NaN
dtype: object

When using expand=True, the split elements will expand out into separate columns. If NaN is present, it is propagated throughout the columns during the split.

>>> s.str.split(expand=True)
                                               0     1     2        3         4
0                                           this    is     a  regular  sentence
1  https://docs.python.org/3/tutorial/index.html  None  None     None      None
2                                            NaN   NaN   NaN      NaN       NaN

For slightly more complex use cases like splitting the html document name from a url, a combination of parameter settings can be used.

>>> s.str.rsplit("/", n=1, expand=True)
                                    0           1
0          this is a regular sentence        None
1  https://docs.python.org/3/tutorial  index.html
2                                 NaN         NaN

Remember to escape special characters when explicitly using regular expressions.

>>> s = pd.Series(["foo and bar plus baz"])
>>> s.str.split(r"and|plus", expand=True)
    0   1   2
0 foo bar baz

Regular expressions can be used to handle urls or file names. When pat is a string and regex=None (the default), the given pat is compiled as a regex only if len(pat) != 1.

>>> s = pd.Series(['foojpgbar.jpg'])
>>> s.str.split(r".", expand=True)
           0    1
0  foojpgbar  jpg

>>> s.str.split(r"\.jpg", expand=True)
           0 1
0  foojpgbar

When regex=True, pat is interpreted as a regex

>>> s.str.split(r"\.jpg", regex=True, expand=True)
           0 1
0  foojpgbar

A compiled regex can be passed as pat

>>> import re
>>> s.str.split(re.compile(r"\.jpg"), expand=True)
           0 1
0  foojpgbar

When regex=False, pat is interpreted as the string itself

>>> s.str.split(r"\.jpg", regex=False, expand=True)
               0
0  foojpgbar.jpg