Convert object data type to string issue in python

Question

How can I convert an object dtype structure to a string dtype? The method below is not working and the column remains object after converting to a string with .astype

import pandas as pd
df = pd.DataFrame({'country': ['A', 'B', 'C', 'D', 'E']})

df.dtypes
#country    object
#dtype: object

df['county'] = df['country'].astype(str)

df.dtypes
#country    object
#dtype: object

pandas V 1.0 introduced StringDtype - check the docs for more info on dtypes. — Chris Adams
– Chris Adams, Commented Mar 7, 2020 at 20:29

ALollz · Accepted Answer · 2020-05-07 17:53:37Z

16

object is the default container capable of holding strings, or any combination of dtypes.

If you are using a version of pandas < '1.0.0' this is your only option. If you are using pd.__version__ >= '1.0.0' then you can use the new experimental pd.StringDtype() dtype. Being experimental, the behavior is subject to change in future versions, so use at your own risk.

df.dtypes
#country    object

# .astype(str) and .astype('str') keep the column as object. 
df['country'] = df['country'].astype(str)
df.dtypes
#country    object

df['country'] = df['country'].astype(pd.StringDtype())
df.dtypes
#country    string

edited May 7, 2020 at 17:53

answered Mar 7, 2020 at 20:31

ALollz

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1 Comment

Simone Over a year ago

Thanks for sharing and the link to the reference manual. Adapted the example from the manual pd.Series(['abc', None, 'def'], dtype=pd.StringDtype()) . It worked when everything else failed, e.g. see here or here or here

ALollz · Accepted Answer · 2020-03-30 18:07:53Z

10

I got it to work using 'string' instead of str

df['country'] = df['country'].astype('string')
df.dtypes
#country    string

edited Mar 30, 2020 at 18:07

ALollz

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answered Mar 7, 2020 at 20:41

aakarsh

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1 Comment

jtlz2 Over a year ago

Amazing - but what stopped/would stop str working - null values perhaps?

Ukrainian-serge · Accepted Answer · 2020-03-07 20:31:25Z

0

You are converting it to a str. non-null object is how pandas handles str in some cases.

Check out this article on pandas data types.

Check out the most recent official docs on dtypes.

answered Mar 7, 2020 at 20:31

Ukrainian-serge

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