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sum() function in Python

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The sum of numbers in the list is required everywhere. Python provides an inbuilt function sum() which sums up the numbers in the list. 

Sum() Function in Python Syntax

Syntax : sum(iterable, start)  

  • iterable : iterable can be anything list , tuples or dictionaries , but most importantly it should be numbers.
  • start : this start is added to the sum of  numbers in the iterable. If start is not given in the syntax , it is assumed to be 0.

Possible two more syntaxes

sum(a) :  a is the list , it adds up all the numbers in the list a and takes start to be 0, so returning only the sum of the numbers in the list.
sum(a, start) : this returns the sum of the list + start The sum

Python Sum() Function Examples

Get the sum of the list in Python.

Python3

numbers = [1,2,3,4,5,1,4,5]
 
Sum = sum(numbers)
print(Sum)
 
Sum = sum(numbers, 10)
print(Sum)

                    

Output:

25
35

Here below we cover some examples using the sum function with different datatypes in Python to calculate the sum of the data in the given input

  • Sum Function on a Dictionary 
  • Sum Function on a Set
  • Sum Function on a Tuple
  • The sum in Python with For Loop
  • Error and Exceptions
  • Practical Application 

Python Sum Function on a Dictionary 

In this example, we are creating a tuple of 5 numbers and using sum() on the dictionary in Python.

Python3

my_dict = {'a': 10, 'b': 20, 'c': 30}
total = sum(my_dict.values())
print(total)

                    

Output :

60

Time complexity: O(1)
Space complexity: O(n)

Python Sum Function on a Set

In this example, we are creating a tuple of 5 numbers and using sum() on the set in Python.

Python3

my_set = {1, 2, 3, 4, 5}
total = sum(my_set)
print(total)

                    

Output :

15

Python Sum Function on a Tuple

In this example, we are creating a tuple of 5 numbers and using sum() on the tuple in Python.

Python3

my_tuple = (1, 2, 3, 4, 5)
total = sum(my_tuple)
print(total)

                    

Output :

15

Time complexity: O(1)
Space complexity: O(n)

The sum in Python with For Loop

In this, the code first defines a list of numbers. It then initializes a variable called total to 0. The code then iterates through the list using a for loop, and for each number in the list, it adds that number to the total variable. Finally, the code prints the total value, which is the sum of the numbers in the list.

Python3

# Define a list of numbers
numbers = [10, 20, 30, 40, 50]
 
# Initialize a variable to store the sum
total = 0
 
# Iterate through the list and add each number to the total
for num in numbers:
    total += num
 
# Print the sum of the numbers
print("The sum of the numbers is:", total)

                    

Output :

The sum of the numbers is: 150

Time complexity: O(n)
Space complexity: O(n)

Error and Exceptions

TypeError: This error is raised when there is anything other than numbers in the list. In the given example we are using a list of strings rather than an integer. 

Python3

arr = ["a"]
 
# start parameter is not provided
Sum = sum(arr)
print(Sum)
 
# start = 10
Sum = sum(arr, 10)
print(Sum)

                    

Output :

Traceback (most recent call last):
  File "/home/23f0f6c9e022aa96d6c560a7eb4cf387.py", line 6, in 
    Sum = sum(arr)
TypeError: unsupported operand type(s) for +: 'int' and 'str'

Practical Application 

Problems where we require the sum to be calculated to do further operations such as finding out the average of numbers. 

Python3

numbers = [1,2,3,4,5,1,4,5]
 
# start = 10
Sum = sum(numbers)
average= Sum/len(numbers)
print (average)

                    

Output

3


Last Updated : 14 Aug, 2023
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