Python Coding challenge - Day 616| What is the output of the following Python Code?

 

Code Explanation:

1. Importing the heapq Module

import heapq

The heapq module provides an implementation of the heap queue algorithm.

It's mainly used to get largest or smallest elements efficiently from a dataset.

2. Defining the Function: top_n()

def top_n(nums, n=2):

This defines a function named top_n.

It takes two arguments:

nums: a list of numbers.

n: the number of top elements to return (default is 2).

3. Using heapq.nlargest() and Generator Expression

 return (x for x in heapq.nlargest(n, nums))

heapq.nlargest(n, nums) returns the n largest elements from the list nums, in descending order.

This line wraps that result in a generator expression:

(x for x in ...) lazily yields each value one-by-one (memory efficient).

This means values aren’t immediately stored in a list until explicitly asked.

Example:

For nums = [5, 1, 9, 3] and n = 2:

heapq.nlargest(2, [5, 1, 9, 3]) → [9, 5]

The generator yields: 9, 5

4. Calling the Function and Printing Result

print(list(top_n([5, 1, 9, 3], 2)))

top_n([5, 1, 9, 3], 2) returns a generator that yields [9, 5].

list(...) converts the generator to a list.

Finally, it prints the list.

Output:

[9, 5]

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