I've a general function, for example (only a simplified example):

def do_operation(operation, a, b, name):
  print name
  do_something_more(a,b,name, operation(a,b))

def operation_x(a,b):
  return a**2 + b

def operation_y(a,b):
  return a**10 - b/2.

and some data:

data = {"first": {"name": "first summation", "a": 10, "b": 20, "operation": operation_x},
        "second": {"name": "second summation", "a": 20, "b": 50, "operation": operation_y},
        "third": {"name": "third summation", "a": 20, "b": 50, "operation": operation_x},   # <-- operation_x again
       }

now I can do:

what_to_do = ("first", "third") # this comes from command line

for sum_id in what_to_do:
    do_operation(data["operation"], data["a"], data["b"], data["name"])

or maybe it's better if I use functools.partial?

from functools import partial
do_operation_one = do_operation(name=data["first"]["name"], operation=data["first"]["operation"], a=data["first"]["a"], b=data["first"]["b"])
do_operation_two = do_operation(name=data["second"]["name"], operation=data["second"]["operation"] a=data["second"]["a"], b=data["second"]["b"])
do_operation_three = do_operation(name=data["third"]["name"], operation=data["third"]["operation"] a=data["third"]["a"], b=data["third"]["b"])

do_dictionary = { "first": do_operation_one,
                  "second": do_operation_two,
                  "third": do_operation_three }

for what in what_to_do:
  do_dictionary[what]()