如何在不使用 function 中内置的求和和使用嵌套循环的情况下添加嵌套列表的值

Question

I have the following line of code

grades=[[54,67,18,19],[89,98,99,98],[26,16,13]]

How can I add the values of each nested list without using the sum built in method and using a nested for loop?

Answer 1

grades=[[54,67,18,19],[89,98,99,98],[26,16,13]]

sum = 0 # Acumulator
for l in grades: # For each list in grades
    for g in l:  # For each grade in current list
        sum += g # Sum current grade into the acumulator
print(sum) # Return 597

Answer 2

How can I add the values of each nested list

see below (assuming you want to sum each nested list)

totals = []
avg = []
grades=[[54,67,18,19],[89,98,99,98],[26,16,13]]
for g in grades:
  totals.append(0)
  for x in g:
    totals[-1] += x
  avg.append(totals[-1]/len(g))
print(totals)

output

[158, 384, 55]

Answer 3

You can make use of reduce to find the sum of elements in the list as below:

import functools 

grades=[[54,67,18,19],[89,98,99,98],[26,16,13]]

total = 0
res = []

for grade in grades:    
   res.append(functools.reduce(lambda x, y: x+y, grade))
print(res) #[158, 384, 55]