Python list filtering with arguments

Question

Is there a way in python to call filter on a list where the filtering function has a number of arguments bound during the call. For example is there a way to do something like this:

>> def foo(a,b,c):
    return a < b and b < c

>> myList = (1,2,3,4,5,6)

>> filter(foo(a=1,c=4),myList)
>> (2,3)

This is to say is there a way to call foo such that a=1, c=4, and b gets bound to the values in myList?

Asked By: kscottz

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Source

Answer 1

One approach is to use lambda:

>>> def foo(a, b, c):
...     return a < b and b < c
... 
>>> myTuple = (1, 2, 3, 4, 5, 6)
>>> filter(lambda x: foo(1, x, 4), myTuple)
(2, 3)

Another is to use partial:

>>> from functools import partial
>>> filter(partial(foo, 1, c=4), myTuple)
(2, 3)

Answered By: senderle

Answer 2

You can create a closure for this purpose:

def makefilter(a, c):
   def myfilter(x):
       return a < x < c
   return myfilter

filter14 = makefilter(1, 4)

myList = [1, 2, 3, 4, 5, 6]
filter(filter14, myList)
>>> [2, 3]

Answered By: Zaur Nasibov

Answer 3

def foo(a,c):
    return lambda b : a < b and b < c

myList = (1,2,3,4,5,6)

g = filter(foo(1,4),myList)

Answered By: Zippo Lee

Python list filtering with arguments

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