JS numerical type array deduplication

This time I will bring you the deduplication of JS numerical type arrays. What are the precautions for deduplication of JS numerical type arrays? The following is a practical case, let’s take a look.

Preface

This article mainly introduces the relevant content about constructing a binary tree with js to deduplicate and optimize numerical arrays. It is shared for your reference. Learning, I won’t say much more below, let’s take a look at the detailed introduction.

Common two-layer loop to implement array deduplication

let arr = [11, 12, 13, 9, 8, 7, 0, 1, 2, 2, 5, 7, 11, 11, 7, 6, 4, 5, 2, 2]
let newArr = []
for (let i = 0; i <p style="text-align: left;"><span style="color: #ff0000"><strong>Build a binary tree to achieve deduplication (only applicable to numeric types array)</strong></span></p><p style="text-align: left;">Construct the previously traversed elements into a binary tree. Each node in the tree satisfies: the value of the left child node</p><p style="text-align: left;">This optimizes the process of determining whether the element has appeared before</p><p style="text-align: left;">If the element is larger than the current node, you only need to determine whether the element is in the right subtree of the node It only needs to appear before</p><p style="text-align: left;">If the element is smaller than the current node, you only need to determine whether the element has appeared in the left subtree of the node</p><pre class="brush:php;toolbar:false">let arr = [0, 1, 2, 2, 5, 7, 11, 7, 6, 4,5, 2, 2]
class Node {
 constructor(value) {
  this.value = value
  this.left = null
  this.right = null
 }
}
class BinaryTree {
 constructor() {
  this.root = null
  this.arr = []
 }
 insert(value) {
  let node = new Node(value)
  if (!this.root) {
   this.root = node
   this.arr.push(value)
   return this.arr
  }
  let current = this.root
  while (true) {
   if (value > current.value) {
    if (current.right) {
     current = current.right
    } else {
     current.right = node
     this.arr.push(value)
     break
    }
   }
   if (value <p style="text-align: left;"><span style="color: #ff0000"><strong>Optimization ideas 1. Record the maximum and minimum values</strong></span></p><p style="text-align: left;">Record the maximum and minimum values ​​of the inserted elements. If it is larger than the largest element or smaller than the smallest element, insert it directly</p><pre class="brush:php;toolbar:false">let arr = [11, 12, 13, 9, 8, 7, 0, 1, 2, 2, 5, 7, 11, 11, 7, 6, 4, 5, 2, 2]
class Node {
 constructor(value) {
  this.value = value
  this.left = null
  this.right = null
 }
}
class BinaryTree {
 constructor() {
  this.root = null
  this.arr = []
  this.max = null
  this.min = null
 }
 insert(value) {
  let node = new Node(value)
  if (!this.root) {
   this.root = node
   this.arr.push(value)
   this.max = value
   this.min = value
   return this.arr
  }
  if (value > this.max) {
   this.arr.push(value)
   this.max = value
   this.findMax().right = node
   return this.arr
  }
  if (value  current.value) {
    if (current.right) {
     current = current.right
    } else {
     current.right = node
     this.arr.push(value)
     break
    }
   }
   if (value <p style="text-align: left;"><span style="color: #ff0000"><strong>Optimization idea two, build a red-black tree</strong></span></p><p style="text-align: left;">Build a red-black tree, balance the height of the tree</p><p style="text-align: left;">For information about red-black trees, please see red-black Insertion of tree</p><pre class="brush:php;toolbar:false">let arr = [11, 12, 13, 9, 8, 7, 0, 1, 2, 2, 5, 7, 11, 11, 7, 6, 4, 5, 2, 2]
console.log(Array.from(new Set(arr)))
class Node {
 constructor(value) {
  this.value = value
  this.left = null
  this.right = null
  this.parent = null
  this.color = 'red'
 }
}
class RedBlackTree {
 constructor() {
  this.root = null
  this.arr = []
 }
 insert(value) {
  let node = new Node(value)
  if (!this.root) {
   node.color = 'black'
   this.root = node
   this.arr.push(value)
   return this
  }
  let cur = this.root
  let inserted = false
  while (true) {
   if (value > cur.value) {
    if (cur.right) {
     cur = cur.right
    } else {
     cur.right = node
     this.arr.push(value)
     node.parent = cur
     inserted = true
     break
    }
   }
   if (value <p style="text-align: left;"><span style="color: #ff0000"><strong>Other deduplication methods</strong></span></p><p style="text-align: left;">##Deduplication through Set object<strong></strong></p><pre class="brush:php;toolbar:false">[...new Set(arr)]

Use

sort() reduce() method to remove duplicates

After sorting, compare adjacent elements to see if they are the same. If they are different, add them to the returned array

It is worth noting that when sorting, the default

compare(2, '2') returns 0; and when reduce(), perform congruent comparison

let arr = [0, 1, 2, '2', 2, 5, 7, 11, 7, 5, 2, '2', 2]
let newArr = []
arr.sort((a, b) => {
 let res = a - b
 if (res !== 0) {
  return res
 } else {
  if (a === b) {
   return 0
  } else {
   if (typeof a === 'number') {
    return -1
   } else {
    return 1
   }
  }
 }
}).reduce((pre, cur) => {
 if (pre !== cur) {
  newArr.push(cur)
  return cur
 }
 return pre
}, null)

pass

includes() map() Method to remove duplicates

let arr = [0, 1, 2, '2', 2, 5, 7, 11, 7, 5, 2, '2', 2]
let newArr = []
arr.map(a => !newArr.includes(a) && newArr.push(a))

By

includes() reduce() Method to remove duplicates

let arr = [0, 1, 2, '2', 2, 5, 7, 11, 7, 5, 2, '2', 2]
let newArr = arr.reduce((pre, cur) => {
  !pre.includes(cur) && pre.push(cur)
  return pre
}, [])

Deduplication of JSON object methods through object key values

let arr = [0, 1, 2, '2', 2, 5, 7, 11, 7, 5, 2, '2', 2]
let obj = {}
arr.map(a => {
  if(!obj[JSON.stringify(a)]){
    obj[JSON.stringify(a)] = 1
  }
})
console.log(Object.keys(obj).map(a => JSON.parse(a)))

I believe you have mastered the method after reading the case in this article. For more exciting information, please pay attention to other related articles on the PHP Chinese website!

Recommended reading:

Basic performance optimization of front-end web pages

##How to use mixed development of android and HTML

The above is the detailed content of JS numerical type array deduplication. For more information, please follow other related articles on the PHP Chinese website!