How do I use different variables depending on the input of a function?-CodePudding

I'm trying to give a number to a function where that number will be used to determine which variables will be used. I think it would look something like this:

num1 = 61
nun2 = 48
num3 = 27

char1 = "a"
char2 = "b"
char3 = "c"

color1 = "red"
color2 = "blue"
color3 = "green"

def func (inputnumber):

    # don't know what to put in here

    return [num,char,color]

I have a set of variables numbers 1,2, and 3. For my function, I will give an input of 1,2, or 3 (I guess it has to be str(inputnumber))and the function will take that number and determine which variables to use to process data. For example, if I input 1, I would like to get a list of [61, "a","red].

Is there a way to do this? I do know about dictionaries but I don't want to make or store new variables and would like to use the ones that already exist.

CodePudding user response：

Do not have those variables in the first place. Instead, use appropriately structured data. Since you want to choose the results according to a numeric index, a list or tuple is appropriate. So to start, instead of separate num1 = 61, num2 = 48, num3 = 27, we could make a single tuple of values: nums = (61, 48, 27). Now we can access that by index, starting at 0: nums[0] is equal to 61, nums[1] is equal to 48, and nums[2] is equal to 27. Since it works the same way regardless of the number, we can use inputnumber to do the selection.

So to start, that gives us:

nums = (61, 48, 27)
chars = ('a', 'b', 'c')
colors = ('red', 'blue', 'green')

def func(selector):
    selector -= 1 # so that input 1 will correspond to index 0 etc.
    return (nums[selector], chars[selector], colors[selector])

However, we can do better. Just like how we are grouping related data to return it, we can group the related possible return values. Use a tuple to represent everything that is returned for a given input. Thus:

results = ((61, 'a', 'red'), (48, 'b', 'blue'), (27, 'c', 'green'))

def func(selector):
    return results[selector-1]

CodePudding user response：

As others have commented, a better, more standard approach would probably be to use a list or dictionary to store the values. That said, if for some reason you really want to refer to variables dynamically by name, you can use the built-in globals() function which returns a dictionary of all global variables keyed by the variable name. You can build that key as string dynamically to access the variable you need. There is also a corresponding locals() function as well if the variables are actually locals instead of a globally scoped.

def func(inputnumber):
   s = str(inputnumber)
   g = globals()
   return [g['num'   s], g['char'   s], g['color'   s]]