Is there a built-in function to determine if instance of a class exists in a list?
Currently I am doing it through a comprehension
>>> class A:
... pass
...
>>> l1=[5,4,3,A(),8]
>>> e=[e for e in l1 if isinstance(e,A)]
Add a comment
|
1 Answer
Return
Trueif any element of the iterable is true. If the iterable is empty, returnFalse.
>>> class A(object): # subclass object for newstyle class (use them everywhere)
pass
>>> l1=[5,4,3,A(),8]
>>> any(isinstance(x, A) for x in l1)
True
By using a generator expresson
(isinstance(x, A) for x in l1)
in conjuction with any, any can short circuit and return True upon finding the first True value (unlike the list comprehension).
3 Comments
mgilson
You might want to mention the benefit of using a generator here is that
any will short-circuit and return True as soon as it finds a True value.
Zac
I suggest you add link to
any documentation: docs.python.org/2/library/functions.html#any
Tanky Woo
Cool, Python suggest use the built-in functions if possible