Apply function Pandas DataFrame without Lambda paramater

Question

df = pd.DataFrame([["Test", "Test123"]] * 3, columns=['A', 'B'])


def shorterstring(string, count): 
    return string[0:-count]


df["A"].apply(lambda x: x[0:2])
Out[614]: 
0    Te
1    Te
2    Te

df["A"].apply(shorterstring(df["A"], 2))
TypeError: 'Series' object is not callable

I want to apply a custom function on a column with strings. I managed to get this to work with the lambda expression, but when I want to apply the function it does not work. Can anyone help me how to do this?

You need to pass to apply the function to use, but instead you're calling shorterstring yourself. Try df["A"].apply(lambda s : shorterstring(s, 2)) (the lambda is still there to reduce your `shorterstring``to a single-parameter function. You could also use functool.partial for that — GPhilo
– GPhilo, Commented Oct 23, 2019 at 10:03

RomanPerekhrest · Accepted Answer · 2019-10-23 10:04:33Z

3

With functools.partial feature:

In [128]: from functools import partial                                                                     

In [129]: df["A"].apply(partial(shorterstring, count=2))                                                    
Out[129]: 
0    Te
1    Te
2    Te
Name: A, dtype: object

answered Oct 23, 2019 at 10:04

RomanPerekhrest

93.1k4 gold badges75 silver badges112 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Apply function Pandas DataFrame without Lambda paramater

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related