Map an if statement in Python

Question

I'm trying to map the following function over a pandas dataframe (basically a list) in python 2.7:

df["Cherbourg"] = df["Embarked"].map(lambda x: if (x == "C") 1 else 0)

But python errors saying using a lambda function like this is a syntax error. Is there some way to map an if statement like this in python?

score 27 · Accepted Answer · edited May 23 '17 at 12:25

27

Try

lambda x: 1 if x == "C" else 0

possible duplicate of Is there a way to perform "if" in python's lambda

Example :

map(lambda x: True if x % 2 == 0 else False, range(1, 11))

result will be - [False, True, False, True, False, True, False, True, False, True]

edited May 23 '17 at 12:25

Community

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answered Mar 25 '15 at 05:00

pnv

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score 5 · Answer 2 · answered Mar 25 '15 at 08:48

5

It will be simpler to just do this:

df["Cherbourg"] = (df["Embarked"] == "C").astype('int)

answered Mar 25 '15 at 08:48

EdChum

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score 1 · Answer 3 · edited Oct 29 '21 at 20:40

1

df["Cherbourg"] = df["Embarked"].apply(lambda x:1 if x == 'C' else 0)

edited Oct 29 '21 at 20:40

j__carlson

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answered Sep 11 '20 at 16:50

raghu

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This solution may work but please add some explanation to support this code solution. Also, please format the code inside backticks (`\``) – tshimkus Sep 11 '20 at 17:42
1

I doubt that this helps or even works at all. Would you like to add an explanation? – Yunnosch Sep 28 '20 at 16:32

score 0 · Answer 4 · answered Aug 25 '22 at 14:28

0

A more readable approach:

def mapping(row):
    if row.Embarked == 'C':
        row.Cherbourg = 1
    else:
        row.Cherbourg = 0
return row
    
df.apply(mapping, axis='columns')

answered Aug 25 '22 at 14:28

Georgi Popov

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Map an if statement in Python

4 Answers4