How to write lambda with a new line in the argument

I don't know how to write Lambda in the argument with a new line.

I would like to write a code that behaves the same as the code below.

import pandas as pd
df = pd.DataFrame(
    {
        'name':('Hoge', 'Bar',
        'value': ('1', '2')
    }
)
conditionally_combine(r):
    ifr ['name'] == 'Hoge':
        return ['name'] + r ['value']
    else:
        return ['name']
df["combine"] = df.apply(lambdar:conditionally_combine(r),axis=1)
print(df)

https://naruport.com/blog/2019/9/5/python-tutorial-lambda/

The lambda formula is basically written in one line.
Therefore, multi-line lambda expressions are not supported.
If you want to write more than one line, escape a new line like ↓.

You cannot write a return statement like ↓ in the lambda formula.

Therefore, I did the following, but it is an error.

File line 11
ifr ['name'] == 'Hoge':
^
SyntaxError: invalid syntax

import pandas as pd

df = pd.DataFrame(
    {
        'name':('Hoge', 'Bar',
        'value': ('1', '2')
    }
)

df["combine"] = df.apply(lambdar:\
        ifr ['name'] == 'Hoge':\
            r['name']+r['value']\
        else:\
            r ['name']
    ,
    axis = 1
)
print(df)

Also

http://www.sakito.com/2012/10/python-lambda.html

Here are some simple samples for now.Sometimes people think Lambda can't break a new line, but if you put it in parentheses, you can break a new line normally.

Therefore, I did the following, but the error was similar.

import pandas as pd

df = pd.DataFrame(
    {
        'name':('Hoge', 'Bar',
        'value': ('1', '2')
    }
)

df["combine"] = df.apply(lambdar:
        ifr ['name'] == 'Hoge':
            r['name'] + r['value']
        else:
            r ['name']
    ),
    axis = 1
)
print(df)

python

2022-09-30 16:45

1 Answers

if is a statement as the comment states if statement (statement).( if appears in the middle of an expression is expression with a conditional expression)

(The relationship between the sentence and the expression is rather complicated, so I can't write everything down, so please refer to the following.)

In Python language reference, ...

6. Expression
- Ramda expression: 6.14.Ramda(lambda)
7.Simple statement
8. Compound statement

Ramda expression: 6.14.Ramda(lambda)

You can write an expression in the expression section, which is summarized in this way and sometimes appears during the description of the statement, statement.In other words…

There is an expression in the statement
A lambda expression is an expression and cannot contain a statement inside it

The following conditional decisions, such as the if statement, can be considered as an expression.

Conditional Expressions
compression
Also Itertools, compress(), filterfalse(), dropwhile(), takewheel() etc. can be used?

Conditional Expressions

compression

Are there any other compress(), filterfalse(), dropwhile(), takewhile(), takewhile() in itertools?

Also, if you use the function well, you may be able to do something in your own way.

import sys
lst = [print('hello'), print('world'), sys.exit(0)] Call by list/dict, etc.
Call by f'{func_a()}{func_b()}{sys.exit(0)}'#f-string

There is also a howto like this, so please refer to it

Functional programming HOWTO

2022-09-30 16:45

If you have any answers or tips

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