Python: Pandas dataframe str replace to partial lower case string

Question

I have the pandas dataframe as below. I only want to dataframe that contains -P to _p(lowe case after that) and '-' remove and change the string after that with lower case.

>>> data= ['AAP','AAPL','BRK-A','AAIC-PB','AAP-C','YAB-PP']
>>> a = pd.DataFrame(data,columns=['code'])
>>> a
      code
0      AAP
1     AAPL
2    BRK-A
3  AAIC-PB
4    AAP-C
5   YAB-PP
>>> a['code']=a['code'].str.replace('-P','_p')
>>> a
>>> a
      code
0      AAP
1     AAPL
2    BRK-A
3  AAIC_pB
4    AAP-C
5   YAB_pP
>>> a['code']=a['code'].str.replace('-','')
>>> a
      code
0      AAP
1     AAPL
2     BRKA
3  AAIC_pB
4     AAPC
5   YAB_pP
>>>

The desired output is

      code
0      AAP
1     AAPL
2    BRKa
3  AAIC_pb
4    AAPc
5   YAB_pp

Please explain why BRK-A becomes BRKa, but YAB-PP becomes YAB_pp — Tim Biegeleisen
– Tim Biegeleisen, Commented Dec 20, 2020 at 9:51
It is a pattern for code conversion. If contains '-', remove it and convert the string after tat with lowercase. If contains '-P', convert to _pand string after that convert to lower case. — bkcollection
– bkcollection, Commented Dec 20, 2020 at 9:55

Dani Mesejo · Accepted Answer · 2020-12-20 10:42:32Z

2

You could do:

import pandas as pd

data= ['AAP','AAPL','BRK-A','AAIC-PB','AAP-C','YAB-PP']
a = pd.DataFrame(data,columns=['code'])


a['code'] = a['code'].str.replace('-(P.*)', lambda x: f'_{x.group(1).lower()}')
a['code'] = a['code'].str.replace('-(\w.*)', lambda x: x.group(1).lower())
print(a)

Output

      code
0      AAP
1     AAPL
2     BRKa
3  AAIC_pb
4     AAPc
5   YAB_pp

UPDATE

In versions previous to Python 3.6:

a['code'] = a['code'].str.replace('-(P.*)', lambda x: '_{}'.format(x.group(1).lower()))
a['code'] = a['code'].str.replace('-(\w.*)', lambda x: x.group(1).lower())
print(a)

edited Dec 20, 2020 at 10:42

answered Dec 20, 2020 at 9:56

Dani Mesejo

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3 Comments

bkcollection Over a year ago

a['code'] = a['code'].str.replace('-(P.*)', lambda x: f'_{x.group(1).lower()}') return SyntaxError: invalid syntax

Dani Mesejo Over a year ago

@bkcollection What Python version are you using?

bkcollection Over a year ago

I am using Python 2.7

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