Find the average of an unknown number of inputs in Python

Prerequisites: *args and **kwargs in Python

The special syntax *args in function definitions in python is used to pass a variable number of arguments to a function. It is used to pass a non-keyword, variable-length argument list. The syntax is to use the symbol * to take in a variable number of arguments; by convention, it is often used with the word args. In this article, the task is to find the average of the unknown number of inputs.

Examples:

Input : 1, 2, 3
Output : 2.00

Input : 2, 6, 4, 8
Output: 5.00

Below is the implementation. 

Python3

# function that takes arbitrary
# number of inputs
def avgfun(*n):
    sums = 0

    for t in n:
        sums = sums + t

    avg = sums / len(n)
    return avg


# Driver Code
result1 = avgfun(1, 2, 3)
result2 = avgfun(2, 6, 4, 8)

# Printing average of the list
print(round(result1, 2))
print(round(result2, 2))

Output:

2.0
5.0

Time complexity: O(n), where n is the number of inputs passed to the function.
Auxiliary space: O(1), as the amount of memory used by the function does not increase with the size of the input.

Method 2: Use the built-in Python function sum() to calculate the sum of the inputs and then divide it by the length of the input to get the average.

Python3

# function that takes arbitrary
# number of inputs


def avgfun(*n):
    return sum(n) / len(n)


# Driver Code
result1 = avgfun(1, 2, 3)
result2 = avgfun(2, 6, 4, 8)

# Printing average of the list
print(round(result1, 2))
print(round(result2, 2))

Output

2.0
5.0

Time Complexity: O(n)
Auxiliary Space: O(1)

Method 3: Use the reduce() function from the functools module.

Step-by-step approach:

• Import the functools module.
• Define a function that takes two arguments, a and b, and returns their sum.
• Use the reduce() function to sum all the input numbers.
• Divide the sum by the length of the input to get the average.
• Return the average.

Below is the implementation of the above approach:

Python3

import functools

def avgfun(*n):
    sum_of_inputs = functools.reduce(lambda a, b: a + b, n)
    avg = sum_of_inputs / len(n)
    return avg

result1 = avgfun(1, 2, 3)
result2 = avgfun(2, 6, 4, 8)

print(round(result1, 2))
print(round(result2, 2))

Time complexity: O(n), where n is the number of input numbers, because it loops through all the inputs once to calculate the sum.
Auxiliary space: O(1) auxiliary space because it only uses a constant amount of memory to store the sum and the average.

Method 4: Using mean() from statistics module in python where we need to pass the list as an argument which will give the average as an output for the given list.

 Step-by-step approach:

• Import the statistics module.
• Use the mean() function to get average.
• Print the average.

Python3

import statistics

result1 = statistics.mean([1, 2, 3])
result2 = statistics.mean([2, 6, 4, 8])

print(result1)
print(result2)

Output

2
5

Time complexity: O(n), where n is the number of input numbers.
Auxiliary space: O(1)