The heapq module in Python provides functions for implementing heaps based on regular lists. Heaps are binary trees for which every parent node has a value less than or equal to any of its children.
Importing heapq
import heapq
Creating a Heap
Initialize a list and convert it into a heap:
numbers = [5, 7, 9, 1, 3]
heapq.heapify(numbers)
print(numbers) # Output: [1, 3, 9, 7, 5]
Adding Elements
Use heappush() to add elements:
heapq.heappush(numbers, 2)
print(numbers) # Output: [1, 2, 9, 7, 5, 3]
Removing Elements
Use heappop() to remove the smallest element:
smallest = heapq.heappop(numbers)
print(smallest) # Output: 1
Finding N Largest or Smallest Elements
Use nlargest() and nsmallest() functions:
largest = heapq.nlargest(2, numbers)
smallest = heapq.nsmallest(2, numbers)
Conclusion
The heapq module is efficient for implementing priority queues and heaps in Python. It provides a simple interface for heap operations.