Lambda including if...elif...else

user_8144295 0
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I want to apply a lambda function to a DataFrame column using if...elif...else within the lambda function.

The df and the code are something like:

df=pd.DataFrame({"one":[1,2,3,4,5],"two":[6,7,8,9,10]})

df["one"].apply(lambda x: x*10 if x<2 elif x<4 x**2 else x+10)

Obviously, this doesn't work. Is there a way to apply if....elif....else to a lambda? How can I get the same result with List Comprehension?

pandas dataframe python
4 Answers

For readability I prefer to write a function, especially if you are dealing with many conditions. For the original question:

def parse_values(x):
    if x < 2:
       return x * 10
    elif x < 4:
       return x ** 2
    else:
       return x + 10

df['one'].apply(parse_values)
user_46918610

You can do it using multiple loc operators. Here is a newly created column labelled 'new' with the conditional calculation applied:

df.loc[(df['one'] < 2), 'new'] = df['one'] * 10
df.loc[(df['one'] < 4), 'new'] = df['one'] ** 2
df.loc[(df['one'] >= 4), 'new'] = df['one'] + 10
user_169679170
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