python - How to translate "bytes" objects into literal strings in pandas Dataframe, Python3.x?

Question

I have a Python3.x pandas DataFrame whereby certain columns are strings which as expressed as bytes (like in Python2.x)

import pandas as pd
df = pd.DataFrame(...)
df
       COLUMN1         ....
0      b'abcde'        ....
1      b'dog'          ....
2      b'cat1'         ....
3      b'bird1'        ....
4      b'elephant1'    ....

When I access by column with df.COLUMN1, I see Name: COLUMN1, dtype: object

However, if I access by element, it is a "bytes" object

df.COLUMN1.ix[0].dtype
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: 'bytes' object has no attribute 'dtype'

How do I convert these into "regular" strings? That is, how can I get rid of this b'' prefix?

Answer 1

You can use vectorised str.decode to decode byte strings into ordinary strings:

df['COLUMN1'].str.decode("utf-8")

To do this for multiple columns you can select just the str columns:

str_df = df.select_dtypes([np.object])

convert all of them:

str_df = str_df.stack().str.decode('utf-8').unstack()

You can then swap out converted cols with the original df cols:

for col in str_df:
    df[col] = str_df[col]