if a function takes n number of arguments, and there is another function that returns a sequence with n number of items(or I have a sequence with n number of items), is there a way to ‘map’ these two functions(or make the first function take a sequence of n number of items as input and return result) I don’t want (and maybe can’t in some occasions) to edit the function myself and change its arguments parameters and return value types.
i.e)
def func1(x, y, z):
return x+y+z
def func2(w):
return [i for i in range(w,w+3)]
cant func1(func2( ... )) in this case.
Answers:
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Method 1
You are looking for the *args argument syntax:
>>> def foo(bar, baz, spam): ... print bar, baz, spam ... >>> arguments = [1, 2, 3] >>> foo(*arguments) 1, 2, 3
When passing arguments to a callable, any expression preceded by a * asterix, is interpreted as a sequence of positional arguments, and expanded to be passed on as separate arguments to the called object (function, method, etc.).
For your example that would be:
func1(*func2(...))
There is a keyword equivalent using ** double asterixes (takes a mapping), and you can use the same syntax in function signatures too.
See the documentation on call expressions, and for the function signature mirror syntax, the documentation on function definitions.
Method 2
It’s called argument unpacking and is written as:
func1(*func2(...))
Refer: https://docs.python.org/2/tutorial/controlflow.html#unpacking-argument-lists
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