拆分pandas列并将新结果附加到数据帧

Question

How can I split a pandas column and append the new results to the dataframe? I also want there to be no white space.

Example of my desired output:

col1
Smith, John
Smith, John

col2               
Smith
Smith

col3
John
John

I been trying this but the lambda function is not appending the results how I want it to.

df_split = df1['col1'].apply(lambda x: pd.Series(x.split(',')))
df1['col2']= df_split.apply(lambda x: x[0])
df1['col3']= df_split.apply(lambda x: x[1])

I end up getting

col2  col3
Smith Smith
John  John

Answer 1

Use Series.str.split(..., expand=True) :

df[['col2', 'col3']] = df.col1.str.split(',\s+', expand=True); df

          col1   col2  col3
0  Smith, John  Smith  John
1  Smith, John  Smith  John

Answer 2

We can use Series.str.extract() method:

In [157]: df[['col2','col3']] = df['col1'].str.extract('(\w+),\s*(\w+)', expand=True)

In [158]: df
Out[158]:
                 col1        col2   col3
0         Smith, John       Smith   John
1         Smith, John       Smith   John
2  Mustermann,    Max  Mustermann    Max
3          Last,First        Last  First

(\\w+),\\s*(\\w+) is a RegEx (Regular Expression) explained here

Answer 3

If you just want to store first string after split, then use following

df['col2'] = df['col1'].str.split(',', 1).str[0] 

          col1   col2
0  Smith, John  Smith  
1  Smith, John  Smith