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pythonpandasfeature-engineering

How to assign new column based on the list of string values in pandas

I have a dataframe that one of the column contains string values, and I want to assign new column if this column values are in the list I specified.

my_list = ['AA', 'TR', 'NZ']

For example: My dataframe : df

country
AA
TR
SG

The dataframe I want to have:

country flag
AA 1
TR 1
SG 0

I tried this one but I gave an Value Error.

df.assign(flag = lambda df: '1' if df['country'].isin(my_list) else '0')

What should I do? Thank you

Solution

  • You can directly convert your boolean to 0/1 with astype(int):

    df.assign(flag= df['country'].isin(my_list).astype(int))

    Or for a string:

    df.assign(flag= df['country'].isin(my_list).astype(int).astype(str))

    Alternatively, use numpy.where:

    import numpy as np
df.assign(flag=np.where(df['country'].isin(my_list), '1', '0'))

    output:

      country flag
0      AA    1
1      TR    1
2      SG    0