CODEWITHSUNDEEP
pythonlambdafilter
Alexander
Alexander

Reputation: 1378

Iterating over a list of integers using map and using a list of functions

Hi guys Im trying to write a code that uses a list of functions and a list of integers and only returns the ones that have at least 1 true in the list of functions like so:

tuple(lambda func,data:filter(lambda x:map(lambda y:y(x)==true,func),data))

func=(lambda x: x>3,lambda x: x%2==0)
data=(1,2,3,4,5,6,7,8,9,10)

so the list should return 4,6,8,10 but instead it returns the entire list,does anybody knows why?

P.S I know it can be done very easily in a different way, but Its a lambda exercise.

Upvotes: 0

Views: 39

Answers (2)

juanpa.arrivillaga
juanpa.arrivillaga

Reputation: 95957

You can use an expression like the following:

tuple(filter(lambda x: any(filter(lambda f: f(x), func)), data))

So,

In [17]: func=(lambda x: x>3,lambda x: x%2==0)
    ...: data=(1,2,3,4,5,6,7,8,9,10)
    ...:
    ...:

In [18]: tuple(filter(lambda x: any(filter(lambda f: f(x), func)), data))
Out[18]: (2, 4, 5, 6, 7, 8, 9, 10)

Also note, your expression raises a TypeError, so I don't know what you mean about it returning the whole list.

It would probably be more readable to use something like:

In [23]: tuple(
    ...:     x for x in data
    ...:     if any(f(x) for f in func)
    ...: )
Out[23]: (2, 4, 5, 6, 7, 8, 9, 10)

Or without any (a ridiculous constraint)

In [29]: tuple(filter(lambda x: tuple(filter(None, map(lambda f: f(x), func))), data))
Out[29]: (2, 4, 5, 6, 7, 8, 9, 10)

Upvotes: 1

mVChr
mVChr

Reputation: 50185

It's more Pythonic to map these functions using list comprehensions:

data = range(1, 11)
funcs = (lambda x: x > 3, lambda x: x % 2 == 0)
new_data = [x for x in l if all(f(x) for f in funcs)]
# new_data == [4, 6, 8, 10]

Upvotes: 0

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