67

What is a good, brief way to extract items from a list and pass them as parameters to a function call, such as in the example below?

Example:

def add(a,b,c,d,e):
    print(a,b,c,d,e)

x=(1,2,3,4,5)

add(magic_function(x))
Zero Piraeus
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falek.marcin
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3 Answers3

100

You can unpack a tuple or a list into positional arguments using a star.

def add(a, b, c):
    print(a, b, c)

x = (1, 2, 3)
add(*x)

Similarly, you can use double star to unpack a dict into keyword arguments.

x = { 'a': 3, 'b': 1, 'c': 2 }
add(**x) 
Cat Plus Plus
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17

I think you mean the * unpacking operator:

>>> l = [1,2,3,4,5]
>>> def add(a,b,c,d,e):
...    print(a,b,c,d,e)
...
>>> add(*l)
1 2 3 4 5
Tim Pietzcker
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7

Use the * operator. So add(*x) would do what you want.

See this other SO question for more information.

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arunkumar
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