Question

I have this problem on my study guide that calls for a function that gets the average of two dimensional lists and prints them as one list.
I don’t really have experience messing with two dimensional lists therefore have no clue where to even begin attacking this problem.

example of what it should do:

avrg([[85, 23, 45], [66, 75, 54], [85, 54, 70], [34, 10, 0]])

[51.0, 65.0, 162.333333333334, 14.66666666666667]

my coding:

def avrg(L):
    for i in range(len(L)):
        for j in range(len(L[0])):
            L[i][j] / i

    return L

Where in my coding did I go wrong?

Answer 1

For a start, the expression x / y results in a value but does not change x or y. If you’re using Python, you might also want to think about using the actual list contents in the iteration instead of the more C-like “range” and accessors. Hopefully this should give you a strong push in the right direction to go:

def avrg( inlist ):
    result = []
    for a in inlist:
        # now "a" is just a list by itself
        n = len(a)
        total = sum(a)
        # you can fill in the rest here
    return result