Flatten a list/tuple and Call a function with tuples

Diez B. Roggisch deets at nospam.web.de
Wed Jul 25 18:18:57 CEST 2007


beginner wrote:

> On Jul 25, 10:19 am, Stargaming <stargam... at gmail.com> wrote:
>> On Wed, 25 Jul 2007 14:50:18 +0000, beginner wrote:
>> > Hi,
>>
>> > I am wondering how do I 'flatten' a list or a tuple? For example, I'd
>> > like to transform[1, 2, (3,4)] or [1,2,[3,4]] to  [1,2,3,4].
>>
>> A recursive function, always yielding the first element of the list,
>> could do the job. See the ASPN Python Cookbook for a few
>> implementations.http://aspn.activestate.com/ASPN/search?
>> query=flatten&section=PYTHONCKBK&type=Subsection
>>
>> > Another question is how do I pass a tuple or list of all the aurgements
>> > of a function to the function. For example, I have all the arguments of
>> > a function in a tuple a=(1,2,3). Then I want to pass each item in the
>> > tuple to a function f so that I make a function call f(1,2,3). In perl
>> > it is a given, but in python, I haven't figured out a way to do it.
>> > (Maybe apply? but it is deprecated?)
>> >>> def foo(a, b, c): print a, b, c
>> ...
>> >>> t = (1, 2, 3)
>> >>> foo(*t)
>>
>> 1 2 3
>>
>> Have a look at the official tutorial, 4.7.4http://www.python.org/doc/
>> current/tut/node6.html#SECTION006740000000000000000
>>
>> > Thanks,
>> > cg
>>
>> HTH,
>> Stargaming
> 
> Hi Stargaming,
> 
> I know the * operator. However, a 'partial unpack' does not seem to
> work.
> 
> def g():
>   return (1,2)
> 
> def f(a,b,c):
>   return a+b+c
> 
> f(*g(),10) will return an error.
> 
> Do you know how to get that to work?

f(*(g() + (10,))

Not the most beautiful solution, but it works.

Diez



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