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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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