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Python Program to Find Sum of Array

In this tutorial, we will learn how to find the sum of all the elements in an array. Before moving further it is necessary that you are familiar with loops in Python.

Python arrays are a data structure like lists, which store homogenous data. Arrays stores objects of the same datatype. Arrays are mutable, meaning that the data in an array can be changed and iterative, meaning each element in an array can be accessed one by one.

In python, you need to import the array module to create an array. The array(data_type, value) function is used to specify an array with its data type and value list given as arguments. Look at the example given below for creating an array in Python.

import array as ar
a = ar.array('i', [1, 3, 5])

Here, we have declared an array of integer types with the value list [1, 3, 5]. The letter i is a type code. This determines the type of the array during creation.

Commonly used type codes are

Code Python Type
i integer
u unicode
f float
l integer


The program should take input and give output as follows:

Input- arr[] = {15,12,13,10}

Output- 50

Approach to Find Sum of Array

For executing this task we can follow two approaches:

  1. Using a loop to calculate sum
  2. Using built-in sum() function

Approach 1: Using looping statement

In this approach, we will use a loop that will run from the starting to the ending index of the array and add all the elements individually.

Algorithm

Step 1- Import array module

Step 2- Define a function to calculate the sum of elements in an array

Step 3- Declare a variable to store the sum

Step 4- Calculate the length of the array using len() function

Step 5 - Run a loop for all the elements in the array

Step 6- Add each element to the variable for sum one by one

Step 7- Return sum

Step 8- Declare the array

Step 9- Call function

Step 10- Print the result

Python Program 1

Look at the program to understand the implementation of the above-mentioned approach.

import array as ar

def SumofArray(arr):
    sum=0
    n = len(arr)
    for i in range(n):
        sum = sum + arr[i]
    return sum
  
#input values to list 
a = ar.array('i',[10, 21, 12, 13])
  
# display sum 
print ('Sum of the array is ', SumofArray(a) ) 


Sum of the array is 56

Approach 2: Using sum() function

In this approach, we will use a built-in function called sum() which calculates the sum of all the elements in an array and returns the result.

Algorithm

Step 1- Import array module

Step 2- Declare array using the module

Step 3- Call sum() function

Step 4- Print the result

Python Program 2

Look at the program to understand the implementation of the above-mentioned approach.

import array as arr
  
#input values 
a = arr.array('i',[10, 21, 12, 13])
  
# display sum 
print ('Sum of the array is ', sum(a) ) 


Sum of the array is 56

Conclusion

In this tutorial, we have learned, two approaches by which we can calculate the sum of all the elements in the array. One, by using a loop to add the elements. Second, by using a predefined function sum() in the Python Library.