Pandas Series: str.rsplit() function

Last update on September 15 2022 12:54:54 (UTC/GMT +8 hours)

Series-str.rsplit() function

The str.rsplit() function is used to split strings around given separator/delimiter.
Splits the string in the Series/Index from the end, at the specified delimiter string. Equivalent to str.rsplit().

Syntax:

Series.str.rsplit(self, pat=None, n=-1, expand=False)

Parameters:

Name	Description	Type/Default Value	Required / Optional
pat	String or regular expression to split on. If not specified, split on whitespace.	str	Optional
n	Limit number of splits in output. None, 0 and -1 will be interpreted as return all splits.	int, default -1 (all)	Required
expand	Expand the splitted strings into separate columns. If True, return DataFrame/MultiIndex expanding dimensionality. If False, return Series/Index, containing lists of strings.	bool, default False	Required

Returns: Series, Index, DataFrame or MultiIndex
Type matches caller unless expand=True (see Notes).

Note:
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.

Example - In the default setting, the string is split by whitespace:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(["this is my new pen",
               "https://www.w3resource.com/pandas/index.php",
               np.nan])
s.str.split()

Output:

0                         [this, is, my, new, pen]
1    [https://www.w3resource.com/pandas/index.php]
2                                              NaN
dtype: object

Example - Without the n parameter, the outputs of rsplit and split are identical:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(["this is my new pen",
               "https://www.w3resource.com/pandas/index.php",
               np.nan])
s.str.rsplit()

Output:

0                         [this, is, my, new, pen]
1    [https://www.w3resource.com/pandas/index.php]
2                                              NaN
dtype: object

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

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(["this is my new pen",
               "https://www.w3resource.com/pandas/index.php",
               np.nan])
s.str.split(n=2)

Output:

0                           [this, is, my new pen]
1    [https://www.w3resource.com/pandas/index.php]
2                                              NaN
dtype: object

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(["this is my new pen",
               "https://www.w3resource.com/pandas/index.php",
               np.nan])
s.str.rsplit(n=2)

Output:

0                           [this is my, new, pen]
1    [https://www.w3resource.com/pandas/index.php]
2                                              NaN
dtype: object

Example - The pat parameter can be used to split by other characters:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(["this is my new pen",
               "https://www.w3resource.com/pandas/index.php",
               np.nan])
s.str.split(pat = "/")

Output:

0                                 [this is my new pen]
1    [https:, , www.w3resource.com, pandas, index.php]
2                                                  NaN
dtype: object

Example - 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:

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(["this is my new pen",
               "https://www.w3resource.com/pandas/index.php",
               np.nan])
s.str.split(expand=True)

Output:

                                            0	   1	   2	   3	  4
0	this	is	my	new	pen
1	https://www.w3resource.com/pandas/index.php	 None	None	None	None
2	NaN	NaN	NaN	NaN	NaN

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

Python-Pandas Code:

import numpy as np
import pandas as pd
s = pd.Series(["this is my new pen",
               "https://www.w3resource.com/pandas/index.php",
               np.nan])
s.str.rsplit("/", n=1, expand=True)

Output:

                                            0	  1
0	                       this is my new pen	None
1	        https://www.w3resource.com/pandas	index.php
2	                                      NaN	NaN

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