The put(priority_number, data) function of PriorityQueue class inserts an item in the queue. In this code, the constructor PriorityQueue() creates a priority queue and stores it in the variable p_queue. Using the queue module is the simplest usage of Priority Queue. Let us create a Priority Queue using the built-in queue module in Python.
This way, we can implement Priority Queue using the default Python dictionary.Ĭreate a dictionary and add items (keys and values): mydict = We will use the key as the priority number of the element and the value to be the value of the queue element. In a Python dictionary, data is stored in pairs that are a key and a value. Now let us sort the tuple using sorted() method: sorted(mytuple) In the following line of code, we will create a tuple and implement Priority Queue with a tuple: mytuple = ((1, "bread"), (3, "pizza"), (2, "apple")) Whereas, the sorted function always returns the sorted sequence and does not disturb the actual sequence of a tuple. The difference between the sort and the sorted methods is that the sort method does not return anything and it makes changes to the actual sequence of the list. To sort out a tuple, we need to use the sorted function. Since you cannot change the elements in a tuple, tuples do not provide a regular sort function like lists. To implement Priority Queue with tuples, we will create a tuple first with elements of a priority queue and then we will sort the tuple.
But the elements of a list are changeable and the elements of a tuple are unchangeable. Both lists and tuples are ordered data structures of Python and allow duplicate values.
Python tuples and lists are the same to some extent. Hence, it takes time to maintain the order of elements according to their priority. List implementation of Priority Queue is not efficient as the list needs to be sorted after every new entry. When the first element is appended to the list, there is no need to sort the list. Just create a list, append elements (key, value), and sort the list every time an element is appended. Implementing a Priority Queue using a list is pretty straightforward. The key quantifies the priority of the element.
#Priority queue python dijkstra how to
How to create a Priority Queue in Python?Īn element in Priority Queue always contains a key and a value. Heap is an implementation of Priority Queue. When implementing Dijkstra’s algorithm, Priority Queue finds the shortest path in a matrix or adjacency list graph efficiently.The smaller the length of the path, the highest is its priority. It keeps track of the unexplored routes and finds the shortest path between different vertices of the graph. In artificial intelligence, Priority Queue implements the A* search algorithm.Priority Queue is used for interrupt handling in operating systems.This makes processing efficient hence introducing parallel computing. Operating systems use the Priority Queue to balance or distribute the load (set of tasks) among different computing units.There are many applications of Priority Queue in the computer world. 10 Python priority queue with a custom comparator.2 How to create a Priority Queue in Python?.
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