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a fast heap-based priority queue in JavaScript
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lemire/FastPriorityQueue.js
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In a priority queue, you can...
- query or remove (poll) the smallest element quickly
- insert elements quickly
In practice, "quickly" often means in logarithmic time (O(log n)).
A heap can be used to implement a priority queue.
FastPriorityQueue is an attempt to implement a performance-oriented priority queuein JavaScript. It can be several times faster than other similar libraries.It is ideal when performance matters.
License: Apache License 2.0
varx=newFastPriorityQueue();x.add(1);x.add(0);x.add(5);x.add(4);x.add(3);x.peek();// should return 0, leaves x unchangedx.size;// should return 5, leaves x unchangedwhile(!x.isEmpty()){console.log(x.poll());}// will print 0 1 3 4 5x.trim();// (optional) optimizes memory usage
You can also provide the constructor with a comparator function.
varx=newFastPriorityQueue(function(a,b){returna>b;});x.add(1);x.add(0);x.add(5);x.add(4);x.add(3);while(!x.isEmpty()){console.log(x.poll());}// will print 5 4 3 1 0
If you are using node.js, you need to import the module:
varFastPriorityQueue=require('fastpriorityqueue');varb=newFastPriorityQueue();// initially emptyb.add(1);// add the value "1"
Instance methods summary:
add(value): add an element into the queue; runs inO(log n)time.poll(): remove and return the element on top of the heap (smallest element); runs inO(log n)time. If the priority queue is empty, the function returnsundefined.remove(value): remove an element matching the provided value, if found, from the queue. The item is matched by using the queue's comparator. Returnstrueif the element is removed,falseotherwise.removeOne(callback): execute the callback function for each item of the queue and remove the first item for which the callback will return true. Returns the removed item, orundefinedif nothing is removed. The callback must be a pure function.removeMany(callback[, limit]): execute the callback function for each item of the queue and remove each item for which the callback will return true, up to a max limit of removed items if specified or no limit if unspecified. Returns an array containing the removed items. The callback must be a pure function.replaceTop(value):poll()andadd(value)in one operation. This is useful forfast, top-k queries. Returns the removed element orundefined, similar topoll().heapify(array): replace the content of the heap with the provided array, then order it based on the comparator.peek(): return the top of the queue (smallest element) without removal, orundefinedif the queue is empty; runs inO(1)time.isEmpty(): returntrueif the the queue has no elements, false otherwise.clone(): copy the priority queue into another, and return it. Queue items are shallow-copied. Runs inO(n)time.forEach(callback): iterate over all items in the priority queue from smallest to largest.callbackshould be a function that accepts two arguments,value(the item), andindex, the zero-based index of the item.trim(): clean up unused memory in the heap; useful after high-churn operations like manyadd()s thenremove()s.
$ npm install fastpriorityqueueThe function calls "add" and "poll" have logarithmic complexity with respectto the size of the data structure (attribute size). Looking at the top valueis a constant time operation.
Using node.js (npm), you can test the code as follows...
$ npm install mocha $ npm testIt tends to fare well against the competition.In some tests, it can be five times faster than any otherJavaScript implementation we could find.
$ node benchmark/test.jsPlatform: darwin 20.1.0 x64Intel(R) Core(TM) i9-9980HK CPU @ 2.40GHzNode version 14.7.0, v8 version 8.4.371.19-node.12Comparing against:js-priority-queue: https://github.com/adamhooper/js-priority-queue 0.1.5stablepriorityqueue: https://github.com/lemire/StablePriorityQueue.js 0.1.2heap.js: https://github.com/qiao/heap.js 0.2.6binaryheapx: https://github.com/xudafeng/BinaryHeap 0.1.1priority_queue: https://github.com/agnat/js_priority_queue 0.1.3js-heap: https://github.com/thauburger/js-heap 0.3.1queue-priority: https://github.com/augustohp/Priority-Queue-NodeJS 1.0.0priorityqueuejs: https://github.com/janogonzalez/priorityqueuejs 2.0.0qheap: https://github.com/andrasq/node-qheap 1.4.0yabh: https://github.com/jmdobry/yabh 1.2.0starting dynamic queue/enqueue benchmarkFastPriorityQueue x 36,816 ops/sec ±0.74% (92 runs sampled)FastPriorityQueue---replaceTop x 107,942 ops/sec ±0.71% (91 runs sampled)sort x 6,240 ops/sec ±1.65% (92 runs sampled)StablePriorityQueue x 10,333 ops/sec ±4.09% (91 runs sampled)js-priority-queue x 14,435 ops/sec ±1.97% (91 runs sampled)heap.js x 6,568 ops/sec ±2.29% (90 runs sampled)binaryheapx x 8,595 ops/sec ±0.56% (94 runs sampled)priority_queue x 8,201 ops/sec ±0.74% (94 runs sampled)js-heap x 557 ops/sec ±1.70% (89 runs sampled)queue-priority x 291 ops/sec ±2.46% (88 runs sampled)priorityqueuejs x 13,864 ops/sec ±2.02% (90 runs sampled)qheap x 26,882 ops/sec ±1.81% (93 runs sampled)yabh x 10,472 ops/sec ±1.50% (93 runs sampled)Fastest is FastPriorityQueueBenchmarks on an Apple M1:
Platform: darwin 20.2.0 arm64Apple M1Node version 15.6.0, v8 version 8.6.395.17-node.23Comparing against:js-priority-queue: https://github.com/adamhooper/js-priority-queue 0.1.5stablepriorityqueue: https://github.com/lemire/StablePriorityQueue.js 0.1.2heap.js: https://github.com/qiao/heap.js 0.2.6binaryheapx: https://github.com/xudafeng/BinaryHeap 0.1.1priority_queue: https://github.com/agnat/js_priority_queue 0.1.3js-heap: https://github.com/thauburger/js-heap 0.3.1queue-priority: https://github.com/augustohp/Priority-Queue-NodeJS 1.0.0priorityqueuejs: https://github.com/janogonzalez/priorityqueuejs 2.0.0qheap: https://github.com/andrasq/node-qheap 1.4.0yabh: https://github.com/jmdobry/yabh 1.2.0starting dynamic queue/enqueue benchmarkFastPriorityQueue x 47,894 ops/sec ±0.19% (100 runs sampled)FastPriorityQueue---replaceTop x 187,809 ops/sec ±0.09% (97 runs sampled)sort x 9,285 ops/sec ±0.10% (100 runs sampled)StablePriorityQueue x 19,830 ops/sec ±0.49% (97 runs sampled)js-priority-queue x 28,382 ops/sec ±0.10% (98 runs sampled)heap.js x 5,504 ops/sec ±0.22% (100 runs sampled)binaryheapx x 10,473 ops/sec ±0.11% (98 runs sampled)priority_queue x 9,041 ops/sec ±0.33% (97 runs sampled)js-heap x 390 ops/sec ±0.04% (96 runs sampled)queue-priority x 438 ops/sec ±0.09% (95 runs sampled)priorityqueuejs x 14,797 ops/sec ±0.07% (101 runs sampled)qheap x 38,108 ops/sec ±0.12% (99 runs sampled)yabh x 14,942 ops/sec ±0.24% (99 runs sampled)Note thatqheap has been updated following the introduction ofFastPriorityQueue, with a reference toFastPriorityQueue which might explains the fact that its performance is comparable toFastPriorityQueue.
A binary heap does not keep track of the insertion order.
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