Security News
New Proposed CISA Mandate Would Require Critical Infrastructure to Report Ransom Payments Within 24 Hours
CISA has proposed a set of new rules that would require critical infrastructure to report cyber incidents and ransom payments.
@datastructures-js/priority-queue
Advanced tools
A heap-based implementation of priority queue in javascript with typescript support.
Weekly downloads
Readme
A heap-based implementation of priority queue in javascript with typescript support.
npm install --save @datastructures-js/priority-queue
PriorityQueue class allows using a compare function between values. MinPriorityQueue & MaxPriorityQueue can be used for primitive values and objects with known comparison prop.
const {
PriorityQueue,
MinPriorityQueue,
MaxPriorityQueue,
} = require('@datastructures-js/priority-queue');
import {
PriorityQueue,
MinPriorityQueue,
MaxPriorityQueue,
ICompare,
IGetCompareValue,
} from '@datastructures-js/priority-queue';
constructor requires a compare function that works similar to javascript sort callback, returning a number bigger than 0, means swap elements.
interface ICar {
year: number;
price: number;
}
const compareCars: ICompare<ICar> = (a: ICar, b: ICar) => {
if (a.year > b.year) {
return -1;
}
if (a.year < b.year) {
// prioritize newest cars
return 1;
}
// with lowest price
return a.price < b.price ? -1 : 1;
};
const carsQueue = new PriorityQueue<ICar>(compareCars);
const carsQueue = new PriorityQueue((a, b) => {
if (a.year > b.year) {
return -1;
}
if (a.year < b.year) {
// prioratize newest cars
return 1;
}
// with lowest price
return a.price < b.price ? -1 : 1;
}
);
constructor requires a callback for object values to indicate which prop is used for comparison, and does not require any for primitive values like numbers or strings.
const numbersQueue = new MinPriorityQueue<number>();
interface IBid {
id: number;
value: number;
}
const getBidValue: IGetCompareValue<IBid> = (bid) => bid.value;
const bidsQueue = new MaxPriorityQueue<IBid>(getBidValue);
const numbersQueue = new MinPriorityQueue();
const bidsQueue = new MaxPriorityQueue((bid) => bid.value);
If the queue is being created from an existing array, and there is no desire to use an extra O(n) space, this static function can turn an array into a priority queue in O(n) runtime.
const numbers = [3, -2, 5, 0, -1, -5, 4];
const pq = PriorityQueue.fromArray<number>(numbers, (a, b) => a - b);
console.log(numbers); // [-5, -1, -2, 3, 0, 5, 4]
pq.dequeue(); // -5
pq.dequeue(); // -2
pq.dequeue(); // -1
console.log(numbers); // [ 0, 3, 4, 5 ]
const numbers = [3, -2, 5, 0, -1, -5, 4];
const pq = PriorityQueue.fromArray(numbers, (a, b) => a - b);
console.log(numbers); // [-5, -1, -2, 3, 0, 5, 4]
pq.dequeue(); // -5
pq.dequeue(); // -2
pq.dequeue(); // -1
console.log(numbers); // [ 0, 3, 4, 5 ]
const numbers = [3, -2, 5, 0, -1, -5, 4];
const mpq = MaxPriorityQueue.fromArray<number>(numbers);
console.log(numbers); // [-5, -1, -2, 3, 0, 5, 4]
mpq.dequeue(); // 5
mpq.dequeue(); // 4
mpq.dequeue(); // 3
console.log(numbers); // [ 0, -1, -5, -2 ]
const numbers = [3, -2, 5, 0, -1, -5, 4];
const mpq = MaxPriorityQueue.fromArray(numbers);
console.log(numbers); // [-5, -1, -2, 3, 0, 5, 4]
mpq.dequeue(); // 5
mpq.dequeue(); // 4
mpq.dequeue(); // 3
console.log(numbers); // [ 0, -1, -5, -2 ]
adds a value based on its comparison with other values in the queue in O(log(n)) runtime.
const cars = [
{ year: 2013, price: 35000 },
{ year: 2010, price: 2000 },
{ year: 2013, price: 30000 },
{ year: 2017, price: 50000 },
{ year: 2013, price: 25000 },
{ year: 2015, price: 40000 },
{ year: 2022, price: 70000 }
];
cars.forEach((car) => carsQueue.enqueue(car));
const numbers = [3, -2, 5, 0, -1, -5, 4];
numbers.forEach((num) => numbersQueue.push(num)); // push is an alias for enqueue
const bids = [
{ id: 1, value: 1000 },
{ id: 2, value: 20000 },
{ id: 3, value: 1000 },
{ id: 4, value: 1500 },
{ id: 5, value: 12000 },
{ id: 6, value: 4000 },
{ id: 7, value: 8000 }
];
bids.forEach((bid) => bidsQueue.enqueue(bid));
peeks on the value with highest priority in the queue.
console.log(carsQueue.front()); // { year: 2022, price: 70000 }
console.log(numbersQueue.front()); // -5
console.log(bidsQueue.front()); // { id: 2, value: 20000 }
peeks on the value with a lowest priority in the queue.
console.log(carsQueue.back()); // { year: 2010, price: 2000 }
console.log(numbersQueue.back()); // 5
console.log(bidsQueue.back()); // { id: 1, value: 1000 }
removes and returns the element with highest priority in the queue in O(log(n)) runtime.
console.log(carsQueue.dequeue()); // { year: 2022, price: 70000 }
console.log(carsQueue.dequeue()); // { year: 2017, price: 50000 }
console.log(carsQueue.dequeue()); // { year: 2015, price: 40000 }
console.log(numbersQueue.dequeue()); // -5
console.log(numbersQueue.dequeue()); // -2
console.log(numbersQueue.dequeue()); // -1
console.log(bidsQueue.pop()); // { id: 2, value: 20000 }
console.log(bidsQueue.pop()); // { id: 5, value: 12000 }
console.log(bidsQueue.pop()); // { id: 7, value: 8000 }
removes all elements that meet a criteria in O(n*log(n)) runtime and returns a list of the removed elements.
carsQueue.remove((car) => car.price === 35000); // [{ year: 2013, price: 35000 }]
numbersQueue.remove((n) => n === 4); // [4]
bidsQueue.remove((bid) => bid.id === 3); // [{ id: 3, value: 1000 }]
checks if the queue is empty.
console.log(carsQueue.isEmpty()); // false
console.log(numbersQueue.isEmpty()); // false
console.log(bidsQueue.isEmpty()); // false
returns the number of elements in the queue.
console.log(carsQueue.size()); // 3
console.log(numbersQueue.size()); // 3
console.log(bidsQueue.size()); // 3
returns a sorted array of elements by their priorities from highest to lowest in O(n*log(n)) runtime.
console.log(carsQueue.toArray());
/*
[
{ year: 2013, price: 25000 },
{ year: 2013, price: 30000 },
{ year: 2010, price: 2000 }
]
*/
console.log(numbersQueue.toArray()); // [ 0, 3, 5 ]
console.log(bidsQueue.toArray());
/*
[
{ id: 6, value: 4000 },
{ id: 4, value: 1500 },
{ id: 1, value: 1000 }
]
*/
The queues implement a Symbol.iterator that makes them iterable on pop
.
console.log([...carsQueue]);
/*
[
{ year: 2013, price: 25000 },
{ year: 2013, price: 30000 },
{ year: 2010, price: 2000 }
]
*/
console.log(carsQueue.size()); // 0
console.log([...numbersQueue]); // [ 0, 3, 5 ]
console.log(numbersQueue.size()); // 0
for (const bid of bidsQueue) {
console.log(bid);
}
/*
{ id: 6, value: 4000 },
{ id: 4, value: 1500 },
{ id: 1, value: 1000 }
*/
console.log(bidsHeap.size()); // 0
clears all elements in the queue.
carsQueue.clear();
console.log(carsQueue.size()); // 0
console.log(carsQueue.front()); // null
console.log(carsQueue.dequeue()); // null
console.log(carsQueue.isEmpty()); // true
numbersQueue.clear();
console.log(numbersQueue.size()); // 0
console.log(numbersQueue.front()); // null
console.log(numbersQueue.dequeue()); // null
console.log(numbersQueue.isEmpty()); // true
bidsQueue.clear();
console.log(bidsQueue.size()); // 0
console.log(bidsQueue.front()); // null
console.log(bidsQueue.dequeue()); // null
console.log(bidsQueue.isEmpty()); // true
grunt build
The MIT License. Full License is here
FAQs
A heap-based implementation of priority queue in javascript with typescript support.
The npm package @datastructures-js/priority-queue receives a total of 44,070 weekly downloads. As such, @datastructures-js/priority-queue popularity was classified as popular.
We found that @datastructures-js/priority-queue demonstrated a healthy version release cadence and project activity because the last version was released less than a year ago. It has 1 open source maintainer collaborating on the project.
Did you know?
Socket for GitHub automatically highlights issues in each pull request and monitors the health of all your open source dependencies. Discover the contents of your packages and block harmful activity before you install or update your dependencies.
Security News
CISA has proposed a set of new rules that would require critical infrastructure to report cyber incidents and ransom payments.
Security News
Redis is no longer OSS, breaking its explicit commitment to remain under the BSD 3-Clause License forever. This has angered contributors who are now working to fork the software.
Product
Socket AI now enables 'AI detected potential malware' alerts by default, ensuring users benefit from AI-powered state-of-the-art malware detection without needing to opt-in.