Python Pandas - Converting data types of columns raises NotImplementedError

Asked Mar 11 '19 at 12:08

Active Mar 11 '19 at 12:08

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I have a DataFrame object with 10 columns. 9 of those columns are of type object, 6 of which I'm trying to convert into type "category", since all of these columns contain a lot of duplicate values. Here's the piece of code for that:

for col in ['Col1', 'Col2', 'Col3', 'Col4', 'Col5', 'Col6']:
    df[col] = df[col].astype('category')

But this code raises the following exception:

File "C:\Python27\lib\site-packages\pandas\core\arrays\categorical.py", line 378, in __init__
raise NotImplementedError("> 1 ndim Categorical are not "
NotImplementedError: > 1 ndim Categorical are not supported at this time

What might be the reason for this error message? I know, there are several questions similar to this one here, but those did not solve my problem. Any help would be much appreciated.

asked Mar 11 '19 at 12:08

Hidayat Rzayev

What is your pandas version? – jezrael Mar 11 '19 at 12:09
@jezrael 0.24.1 – Hidayat Rzayev Mar 11 '19 at 12:11
So how working `cols = ['Col1', 'Col2', 'Col3', 'Col4', 'Col5', 'Col6']` and then `df[cols] = df[cols].astype('category')` ? – jezrael Mar 11 '19 at 12:14
@jezrael Gives the same error message – Hidayat Rzayev Mar 11 '19 at 12:18
@HidayetRzayev please check if you have lists as values within your columns? – Francisco Mar 11 '19 at 12:19
@Francisco All of the values are strings, but some of those strings are enclosed in brackets, e.g. [some text]. Might that cause the problem? – Hidayat Rzayev Mar 11 '19 at 12:26
@HidayetRzayev I'm assuming so. [this link](https://stackoverflow.com/questions/53218931/how-do-i-unnest-explode-a-column-in-a-pandas-dataframe) has a very good post on this. – Francisco Mar 11 '19 at 12:32

Python Pandas - Converting data types of columns raises NotImplementedError

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