CODEWITHSUNDEEP
python-3.xpandas
Konrad
Konrad

Reputation: 23

Python: Create new column with condition and "contains"-Statement

I want to create a new column of a string with a condition. Example:

from pandas import DataFrame
GoT = {'Old_Group': ['Jon Snow', 'Sansa Stark','Arya Stark','Robb Stark','Theon Greyjoy' ]}
df = DataFrame(GoT,columns=['Old_Group'])

The "New_Group" should check if the "Old_Group" contains the String "Stark" on whatever place and assign it to e.g. "Stark Family". If the condition "contains = 'Stark'" does not fit, then the "new_group" should be assigned to e.g. "other"

In SQL I would do it this way:

Select Old_Group
,case when Old_Group like '%Stark%' then 'Stark Family' else 'other' end as New_Group
from df

Thank you

Upvotes: 2

Views: 3172

Answers (3)

Onyambu
Onyambu

Reputation: 79288

In case the name Stark appears in a name like MacStark, then this option would leave it out. Also it is case insensitive

df.assign(New_Column=df.replace({r'(?i)^((?!\bStark\b).)*$':'Other',r'(?i)\bStark\b':'Stark Family'},regex=True))
Out[319]: 
       Old_Group          New_Column
0       Jon Snow               Other
1    Sansa Stark  Sansa Stark Family
2     Arya Stark   Arya Stark Family
3     Robb Stark   Robb Stark Family
4  Theon Greyjoy               Other

Upvotes: 1

Edeki Okoh
Edeki Okoh

Reputation: 1844

You can use a combination of np.where and str.contains to do this. Essentially what you cant to do is apply np.where on the column in question (Old Group in this case) and the check if the string contains the work Stark. 

df['New Group'] = np.where(df['Old Group'].str.contains("Stark"), 'Stark Family', 'Other')

Just make sure your column New Group is a string data type and you have numpy imported as a package

Upvotes: 2

Sociopath
Sociopath

Reputation: 13426

You need:

df['New_Group'] = df['Old_Group'].apply(lambda x : 'Stark Family' if 'Stark' in x else 'other')

print(df)

Output

      Old_Group New_Group                                                                                                                     
0       Jon Snow     other                                                                                                                     
1    Sansa Stark     Stark Family                                                                                                                    
2     Arya Stark     Stark Family                                                                                                                    
3     Robb Stark     Stark Family                                                                                                                    
4  Theon Greyjoy     other

Upvotes: 0

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