Question

Here is part of my module: gm.py

def avg_list(list): 
    sum = 0
    for num in list:
        sum += num

    avg = float(sum)/len(list)
    print avg



def median(list):
    i = len(list)
    if not i%2: # if i divided my 2 has no remainder

        return (list[(i/2)-1]+list[i/2])/2.0 # return the value of this block


    else:
        median = sorted(list)[len(list)/2] # otherwise, when the list is sorted, the index of len(s) / 2 is the middle number.
        return median

When I save this as ‘gm.py’ and open a new script page to input the following function:

import gm
def stats(list):

    stats = {}  # empty dict named stats
    stats['average'] = avg_list(list) # Stats(key)[average] = mean of the list of numbers [values]
    stats['median'] = median(list) # same for median
    return stats

When I run this program and type stats([2,3,4,5,6])… I get an error saying global variable avg_list not defined. I’m not sure if I’m doing the import correctly?
Do I need to do something like… from gm import avg_list() ?

Answer 1

Either reference the functions on the module object:

import gm
def stats(list):

    stats = {}  # empty dict named stats
    stats['average'] = gm.avg_list(list) # Stats(key)[average] = mean of the list of numbers [values]
    stats['median'] = gm.median(list) # same for median
    return stats

or import the functions directly into the global namespace:

from gm import avg_list, median
def stats(list):

    stats = {}  # empty dict named stats
    stats['average'] = avg_list(list) # Stats(key)[average] = mean of the list of numbers [values]
    stats['median'] = median(list) # same for median
    return stats

Note that you should not name a variable list. This masks the built-in list() function / type and can cause confusing errors later if you need to use it.

You can write

stats = {}  # empty dict named stats
stats['average'] = avg_list(list) # Stats(key)[average] = mean of the list of numbers [values]
stats['median'] = median(list) # same for median
return stats

as

stats = {'average': avg_list(list), 'median': median(list)}
return stats # or just return the dict literal, no real need to give it a name.

I think you should look at the first branch of your median function. Does the list need to be sorted there too, like in the second branch?

Your avg_list function is also masking a built-in function, sum(), which you could use here instead of manually adding:

def avg_list(list): 
    avg = float(sum(list))/len(list)
    print avg

Finally, look at the last line of that function — it’s printing the avg, but stats is expecting it to return the avg. The two aren’t the same.