Python: Outputting data from a function called in a function

Question

I have a function called from within a function like this:

def counter(number):
  number = number + 1
  return number

def iterator(iteration, function):
  for i in range(iteration):
    mfunction = function
    output = mfunction()
  return output

I want to call it something like this:

number = 0
number = iterator(5, partial(counter, number))
print number

This returns 1, where as it should return 5, because the count function should have been called 5 times.
I realize that somehow the data isn't outputting correctly but I can't figure out how to return out of the for loop.

This question may seem redundant, because I could easily do something like:

for i in range(5):
  number = counter(number)

But the latter example defeats the purpose of this program.

I think the problem is that I need to create an argument in the counter function to account for the iterator function. But the problem in my actual program is that I would have to modify many functions to do this, and I am trying to avoid that.

I am not that familiar with calling functions inside of functions and any help would be greatly appreciated,

number = number + 1 in counter function does change only the parameter number, not the number outside the function. — falsetru
– falsetru, Commented Nov 10, 2013 at 4:50
partial(counter, number) is equivalent to partial(counter, 0). So the code is calling counter(0) 5 times. — falsetru
– falsetru, Commented Nov 10, 2013 at 4:52
well it prints as 1, so the number is affected. It just doesn't repeat in the for loop. — CodeHard_or_HardCode
– CodeHard_or_HardCode, Commented Nov 10, 2013 at 4:53
It is affected by number = iterator(..). (After the iterator function return = all 5 iteration is done. not after individual call of counter) — falsetru
– falsetru, Commented Nov 10, 2013 at 4:55

falsetru · Accepted Answer · 2013-11-10 05:51:52Z

2

partial(counter, number) is equivalent to partial(counter, 0). So the code is calling counter(0) 5 times.

def counter(number):
    number = number + 1
    return number

def iterator(iteration, function, arg):
    for i in range(iteration):
        arg = function(arg)
    return arg

number = 0
number = iterator(5, counter, number)
print number # => 5

def counter(number, delta):
    number = number + delta
    return number

def iterator(iteration, function, *args):
    args = list(args)
    for i in range(iteration):
        ret = function(*args)
        args[0] = ret
    return ret

number = 0
number = iterator(5, counter, number, 5)
print number # => 25

edited Nov 10, 2013 at 5:51

answered Nov 10, 2013 at 4:58

falsetru

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7 Comments

CodeHard_or_HardCode Over a year ago

This works but the number of arguments is variable which is why I used partial.

falsetru Over a year ago

@NickSimas, Are the number of arguments and the number of return value's items always equal?

CodeHard_or_HardCode Over a year ago

The return is always 1 value. The arguments vary.

falsetru Over a year ago

@NickSimas, You can use Arbitrary Argument Lists. Or you can pass a tuple or a list and use Unpacking Argument list

falsetru Over a year ago

@NickSimas, But that doesn't make sense. counter receives the return value of itself as parameter.

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