Python 3 - Help formatting array/table output

Question

I'm working on a problem but I'm curious about how to better format my output. Basically, I'm working with an array, which in Python is basically a list within a list, or should I say nested lists. The question I'm working on is related to average rating of movies reviews, but lets just say that the first column is a "reviewer" numbered 1-3 or 1-5 (depending on the size of the array) and the movie reviews are the rows, again this is size dependent on the array itself, 3x3, 6x6, etc. So below I will include my code.

array = [[4,6,2,5], [7,9,4,8], [6,9,3,7]]

def review(array):
    'function that outputs average review of movie scores'

    ncols = len(array[0])  #finds number of columns in array 
    total = 0

    for row in array:
        for el in row:
            total+= el
            avg = total/ncols
            print(end = ' ')
        print(' Reviewer average:', avg)

Now, this does work fine as far as calculations go, but what I need to do is have the 'Reviewer Average' number 1, 2, 3, or 1,2,3,4,5 based off the amount of columns in the array, or in other words it should output the column number based off the array size. So for example, a 3x3 array output like the original array in my code above should look like this:

Reviewer 1 average: 4.25
Reviewer 2 average: 11.25
Reviewer 3 average: 17.5

However, as I've stated my issue is, I can't seem to figure out how to number it to work with ANY table/array size, I want it to work regardless if it was 6x6 or 3x3, etc.

My current output looks like:

Reviewer average: 4.25
Reviewer average: 11.25
Reviewer average: 17.5

Apart from not resetting the total, you also seem to be confusing rows and columns. ncols and row in array both refer to the first arrays in array. — Junuxx
– Junuxx, Commented Dec 15, 2015 at 1:04

Nelewout · Accepted Answer · 2015-12-15 01:05:23Z

2

You are not taking the average correctly, so I took the liberty of also solving that issue. Now, as per your question: use enumerate, like so:

array = [[4,6,2,5], [7,9,4,8], [6,9,3,7]]

def review(array):
    'function that outputs average review of movie scores'

    for i, row in enumerate(array, 1):
        avg = sum(row)/len(row)
        print(' Reviewer {0} average: {1}'.format(i, avg))

Output:

 Reviewer 1 average: 4.25
 Reviewer 2 average: 7.0
 Reviewer 3 average: 6.25

Edit: updated code to incorporate erip's comment below.

edited Dec 15, 2015 at 1:05

answered Dec 15, 2015 at 0:52

Nelewout

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5 Comments

erip Over a year ago

You can use enumerate(array, 1) then you don't need i+1

Jabgan Over a year ago

Thanks, is their any other way to do this without enumerate? I'm just curious to learn all possible ways if they exist.

erip Over a year ago

@Jabgan There are ways, but enumerate is the most pythonic.

Nelewout Over a year ago

@erip, thank you. I incorporated your comment into my answer.

Jabgan Over a year ago

@erip Okay fine, what is another way if you're able to answer? I'm still learning so I want to know as many as I can.

erip · Accepted Answer · 2015-12-15 01:01:41Z

0

You can use some more Pythonic constructs:

array = [[4,6,2,5], [7,9,4,8], [6,9,3,7]]
# Reviewer 1's average: (4+6+2+5)/4 = 4.25
# Reviewer 2's average: (7+9+4+8)/4 = 7
# Reviewer 3's average: (6+9+3+7)/4 = 6.25    

def review(array):
    'function that outputs average review of movie scores'

    for i, row in enumerate(array,1):
      average = sum(row) / float(len(row))
      print('Reviewer {} average: {}'.format(i, average))

review(array)

which outputs the correct results:

20:01 $ python test.py
Reviewer 1 average: 4.25
Reviewer 2 average: 7.0
Reviewer 3 average: 6.25

answered Dec 15, 2015 at 1:01

erip

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