How to import a python module inside lambda?

Question

For suppose depending upon the variable I want to import some classes, create its object and return it. for example :

if x=='SomeThing':
  import something
  object = something's object
else:
  import nothing
  object = nothing's object
object.function()

I want to do the above using the lambda how can I do this?

You can't use an import statement inside a lambda expression. — Tal
– Tal, Commented Feb 24, 2020 at 15:59
Why do you want to use a lambda? Just use a standard function def — tomjn
– tomjn, Commented Feb 24, 2020 at 16:01
I want to decrease the size of code that is the only reason behind using lambda — sarath madala
– sarath madala, Commented Feb 24, 2020 at 16:03
No, lambda expressions are used when you don't otherwise need a name for the function being created. The "size of the code" has nothing to do with it. — chepner
– chepner, Commented Feb 24, 2020 at 16:11

Sayandip Dutta · Accepted Answer · 2020-02-24 16:03:33Z

8

You can use magic __import__:

importer = lambda x: (__import__("pandas").DataFrame if x == 0 
                      else __import__('numpy').arange)

NOTE: This is extremely ugly, and not at all recommended, unless you absolutely need to do it.

answered Feb 24, 2020 at 16:03

Sayandip Dutta

15.9k4 gold badges27 silver badges57 bronze badges

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

Comments

chepner · Accepted Answer · 2020-02-24 16:13:55Z

3

It is rarely an issue to simply import both modules unconditionally, and select which module to actually use later.

import something
import nothing

(something if x == 'SomeThing' else nothing).object.function()

If you do need to perform conditional imports, import one or the other, but using the same name.

if x == 'SomeThing':
    import something as thingmodule
else:
    import nothing as thingmodule

thingmodule.object.function()

answered Feb 24, 2020 at 16:13

chepner

538k77 gold badges595 silver badges747 bronze badges