Python: Arguments to sorting function

Question

I am trying to sort a python list of strings. I know that I can use the method sorted and set the attribute key to be a function that implements the behavior I need to sort the elements of the dictionary on. My problem is that this method needs an argument.

UPDATE: I want the method to generalize to multiple arguments.

Example: I want to sort a list of strings based on their priorities in 2 dictionaries . So I need to use those priority dictionaries in sorting the list.

I want something like:

sorted(myList, key=sortingAlgorithm(priorityDictionary1, priorityDictionary2), reverse=True) 

This can be done if I set the priority dictionaries as global variables and then I will not need to have it as an argument to the sorting algorithm. But, I want to be able to do it without global variables.

If this is not possible, can you please recommend the pythonic way of doing this.

Thanks in advance.

Answer 1

Try key=priorityDictionary.get

get is a method on a dictionary that takes a key and returns a value, if one is found.

Edit: The above solution applies to a case of a single dict. Here is a generalization where values of priorityDict2 are keys for priorityDict1.

And, as Padriac Cunningham points out, you can use a lambda to sort using nested dicts:

output = sorted(myList, key=lambda element: priorityDict1[priorityDict2[element]])

Answer 2

Use a closure.

def something(foo):
  def somethingsomething(bar):
    return foo(bar)
  return somethingsomething

baz = something(len)
print baz('quux')