Python Program to find Sum of Elements in a List

Write a Python Program to find the Sum of Elements in a List using the built-in method, for loop, while loop, functions, with a practical example.

This program allows users to enter the length of a List. Next, we used For Loop to add numbers to the list. The sum function returns the sum of all the elements in a List.

NumList = []

Number = int(input("Please enter the Total Number of List Elements : "))
for i in range(1, Number + 1):
    value = int(input("Please enter the Value of %d Element : " %i))
    NumList.append(value)

total = sum(NumList)

print("\n The Sum of All Element in this List is : ", total)
Python Program to find Sum of Elements in a List

Using the math fsum method

import math

numberList = [10, 25, 40, 55, 60, 89, 98]

tot = math.fsum(numberList)

print(tot)
377.0

Using numpy sum function

import numpy as np

numberList = [10, 25, 40, 55, 60, 89, 98]

tot = np.sum(numberList)

print(tot)
377

Using pandas Series

import pandas as pd

numberList = [11, 250, -140, 555, 60, 89, 98]

tot = pd.Series(numberList).sum()

print(tot)
923

Using the statistics fsum method

import statistics

numberList = [11, 250, -340, 955, 690, 829, 98]

tot = statistics.fsum(numberList)

print(tot)
2493.0

Python Program to Find Sum of Elements in a List without using sum() method

In this Python program, we are using For Loop to iterate each element in this NumList. Inside the loop, we are adding those elements to the total variable.

NumList = []
total = 0

Number = int(input("Please enter the Length : "))
for i in range(1, Number + 1):
    value = int(input("Please enter the Value of %d Element : " %i))
    NumList.append(value)

for j in range(Number):
    total = total + NumList[j]

print("\n The Sum of All Element in this List is : ", total)
Please enter the Length : 5
Please enter the Value of 1 Element : 10
Please enter the Value of 2 Element : 20
Please enter the Value of 3 Element : 30
Please enter the Value of 4 Element : 40
Please enter the Value of 5 Element : 55

 The Sum of All Element in this List is :  155

Program to add all elements of a list using for loop

numberList = [20, 40, 50, 60, 80, 90]

tot = 0

for num in numberList:
    tot += num

print(tot)
340

Calculate Sum of List Items using While loop

This program to return the sum of list items is the same as the above. We just replaced the For Loop with a While loop.

NumList = [10, 20, -30, -40, 50, 100]
total = 0
j = 0

while(j < len(NumList)):
    total = total + NumList[j]
    j = j + 1
print(total)

The sum of list items using a while loop output

110

Python Program to find the Sum of Elements in a List using Functions

This program to find the sum of list items is the same as the first example. However, we separated the Python program logic using Functions.

def sum_of_list(NumList):
    total = 0
    for j in range(len(NumList)):
        total = total + NumList[j]
    return total


NumList = [19, 11, 32, 86, 567, 32, 9]

total = sum_of_list(NumList)
print(total)

The sum of list items using functions output

756

An alternative or better approach to writing the above code is shown below.

def sum_of_list(numList):
    total = 0
    for n in numList:
        total += n
    return total

numList = [19, 11, 32, 86, 567, 32, 9]

tot = sum_of_list(numList)
print(tot)
756

using list comprehension

numberList = [22, 49, 222, -150, 160, 820, 97]

tot = sum([n for n in numberList])

print(tot)
1220

using lambda and reduce function

from functools import reduce

numberList = [22, 49, -50, 160, 820, 97]

tot = reduce(lambda x, y: x + y, numberList)

print(tot)
1098

Program to find the Sum of Elements in a List using Recursion

This example code uses the if else statement inside a function and calls the method recursively to calculate the list sum.

def sumOfList(numList):
    if len(numList)  == 1:
        return numList[0]
    else:
        return numList[0] + sumOfList(numList[1:])


numList = [129, 211, 302, -86, 567, 32, 9]
total = sumOfList(numList)
print(total)
1164