ValueError: cannot reindex from a duplicate axis in Python

Dung Do Tien Mar 19 2022 82

 Hello Guys. I am a newbie in Python and I try to learn analytic data by using Pandas package. I have some lines of code as below:

import pandas as pd
import numpy as np

pointers = pd.DataFrame({'points': ['2022-01-10', '2022-02-13', '2022-03-15']})
assists = pd.DataFrame({'assists': ['5', '22', '31']}, index=[0, 1, 1])

pointers['pointsassists'] = pointers['points'] + ' ' + assists['assists']
print(pointers['pointsassists'])

But when run the code above I got an exception throw ValueError: cannot reindex from a duplicate axis .

Traceback (most recent call last):
  File "HelloWorld.py", line 7, in <module>
    wind['pointsassists'] = wind['points'] + ' ' + temp['assists']
  File "/usr/local/lib/python3.6/dist-packages/pandas/core/frame.py", line 3044, in __setitem__
    self._set_item(key, value)
  File "/usr/local/lib/python3.6/dist-packages/pandas/core/frame.py", line 3120, in _set_item
    value = self._sanitize_column(key, value)
  File "/usr/local/lib/python3.6/dist-packages/pandas/core/frame.py", line 3745, in _sanitize_column
    value = reindexer(value)
  File "/usr/local/lib/python3.6/dist-packages/pandas/core/frame.py", line 3736, in reindexer
    raise err
  File "/usr/local/lib/python3.6/dist-packages/pandas/core/frame.py", line 3731, in reindexer
    value = value.reindex(self.index)._values
  File "/usr/local/lib/python3.6/dist-packages/pandas/core/series.py", line 4412, in reindex
    return super().reindex(index=index, **kwargs)
  File "/usr/local/lib/python3.6/dist-packages/pandas/core/generic.py", line 4464, in reindex
    axes, level, limit, tolerance, method, fill_value, copy
  File "/usr/local/lib/python3.6/dist-packages/pandas/core/generic.py", line 4487, in _reindex_axes
    allow_dups=False,
  File "/usr/local/lib/python3.6/dist-packages/pandas/core/generic.py", line 4532, in _reindex_with_indexers
    copy=copy,
  File "/usr/local/lib/python3.6/dist-packages/pandas/core/internals/managers.py", line 1285, in reindex_indexer
    self.axes[axis]._can_reindex(indexer)
  File "/usr/local/lib/python3.6/dist-packages/pandas/core/indexes/base.py", line 3292, in _can_reindex
    raise ValueError("cannot reindex from a duplicate axis")
ValueError: cannot reindex from a duplicate axis

I am using Python 3.9.5 and windows 11. Thanks for any idea!!

Have 1 answer(s) found.
  • E

    Edwin Valle Villegas Mar 19 2022

    You can use reset_index() to help reset the index of DataFrame. Example below:

    pointers = pointers.reset_index(drop=True)

    And here is full code for you:

    import pandas as pd
    import numpy as np
    
    pointers = pd.DataFrame({'points': ['2022-01-10', '2022-02-13', '2022-03-15']})
    assists = pd.DataFrame({'assists': ['5', '22', '31']}, index=[0, 1, 1])
    
    pointers = pointers.reset_index(drop=True)
    assists = assists.reset_index(drop=True)
    
    pointers['pointsassists'] = pointers['points'] + ' ' + assists['assists']
    print(pointers['pointsassists'])

    #Output

    0     2022-01-10 5
    1    2022-02-13 22
    2    2022-03-15 31
    Name: pointsassists, dtype: object

    I hope this answer is helpful for you.

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