在python中查找二维数组的平均值

Question

For one of my coding practices, I need to find the sum and average of an array. I've found a way to get the sum, however I've been struggling to get the code for the average working. Right now I have my code without the average function:

a = [[34,38,50,44,39], 
     [42,36,40,43,44], 
     [24,31,46,40,45], 
     [43,47,35,31,26],
     [37,28,20,36,50]]
     

def sumALL(x):
    sum = 0
    for r in range(len(x)):
        for c in range(len(x[0])):
            sum = sum + a[r][c]

    return sum


print("Sum of all the values: ", sumALL(a))

print("\n\n" + "The average is:  ")

I've found a few things online however they all either deal with numpy, in which the website does not support, or they don't work with the code I've made. I'd like to have the average as a function.

Answer 1

Can't you just use sum() :

sum(a,[])

And to average:

sum(a,[])/sum(len(r) for r in a)

Answer 2

If you are making a separate function for average

def avg(lst):
     lst_el_avg = []
     for i in range(len(lst)):
             lst_el_avg.append(sum(lst[i])/len(lst))
     return sum(lst_el_avg)/len(lst)

Then reference it in your code as follows

print("\n\n" + "The average is:  " + avg(a))

Answer 3

One way to proceed is to flatten the 2d list to 1d list. You can use itertools.chain() to achieve that. Then, you can use sum() and len() to find the average of the elements.

import itertools

a = [[34,38,50,44,39], 
     [42,36,40,43,44], 
     [24,31,46,40,45], 
     [43,47,35,31,26],
     [37,28,20,36,50]]

flat_list = list(itertools.chain(*a))
avg = sum(flat_list) / len(flat_list)

print(avg)

Output

---

37.96