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 < arr.length; i++) {
let unique = true
for (let j = 0; j < newArr.length; j++) {
if (newArr[j] === arr[i]) {
unique = false
break
}
}
if (unique) {
newArr.push(arr[i])
}
}
console.log(newArr)Copy after login
Build a binary tree to achieve deduplication (only applicable to numeric types array)
Construct the previously traversed elements into a binary tree. Each node in the tree satisfies: the value of the left child node< the value of the current node< The value of the right child node
This optimizes the process of determining whether the element has appeared before
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
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
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 < current.value) {
if (current.left) {
current = current.left
} else {
current.left = node
this.arr.push(value)
break
}
}
if (value === current.value) {
break
}
}
return this.arr
}
}
let binaryTree = new BinaryTree()
for (let i = 0; i < arr.length; i++) {
binaryTree.insert(arr[i])
}
console.log(binaryTree.arr)Copy after login
Optimization ideas 1. Record the maximum and minimum values
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
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 < this.min) {
this.arr.push(value)
this.min = value
this.findMin().left = node
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 < current.value) {
if (current.left) {
current = current.left
} else {
current.left = node
this.arr.push(value)
break
}
}
if (value === current.value) {
break
}
}
return this.arr
}
findMax() {
let current = this.root
while (current.right) {
current = current.right
}
return current
}
findMin() {
let current = this.root
while (current.left) {
current = current.left
}
return current
}
}
let binaryTree = new BinaryTree()
for (let i = 0; i < arr.length; i++) {
binaryTree.insert(arr[i])
}
console.log(binaryTree.arr)Copy after login
Optimization idea two, build a red-black tree
Build a red-black tree, balance the height of the tree
For information about red-black trees, please see red-black Insertion of tree
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 < cur.value) {
if (cur.left) {
cur = cur.left
} else {
cur.left = node
this.arr.push(value)
node.parent = cur
inserted = true
break
}
}
if (value === cur.value) {
break
}
}
// 调整树的结构
if(inserted){
this.fixTree(node)
}
return this
}
fixTree(node) {
if (!node.parent) {
node.color = 'black'
this.root = node
return
}
if (node.parent.color === 'black') {
return
}
let son = node
let father = node.parent
let grandFather = father.parent
let directionFtoG = father === grandFather.left ? 'left' : 'right'
let uncle = grandFather[directionFtoG === 'left' ? 'right' : 'left']
let directionStoF = son === father.left ? 'left' : 'right'
if (!uncle || uncle.color === 'black') {
if (directionFtoG === directionStoF) {
if (grandFather.parent) {
grandFather.parent[grandFather.parent.left === grandFather ? 'left' : 'right'] = father
father.parent = grandFather.parent
} else {
this.root = father
father.parent = null
}
father.color = 'black'
grandFather.color = 'red'
father[father.left === son ? 'right' : 'left'] && (father[father.left === son ? 'right' : 'left'].parent = grandFather)
grandFather[grandFather.left === father ? 'left' : 'right'] = father[father.left === son ? 'right' : 'left']
father[father.left === son ? 'right' : 'left'] = grandFather
grandFather.parent = father
return
} else {
grandFather[directionFtoG] = son
son.parent = grandFather
son[directionFtoG] && (son[directionFtoG].parent = father)
father[directionStoF] = son[directionFtoG]
father.parent = son
son[directionFtoG] = father
this.fixTree(father)
}
} else {
father.color = 'black'
uncle.color = 'black'
grandFather.color = 'red'
this.fixTree(grandFather)
}
}
}
let redBlackTree = new RedBlackTree()
for (let i = 0; i < arr.length; i++) {
redBlackTree.insert(arr[i])
}
console.log(redBlackTree.arr)Copy after login
Other deduplication methods
##Deduplication through Set object
[...new Set(arr)]
Copy after login
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)Copy after login
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))
Copy after login
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
}, [])Copy after login
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)))Copy after login
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!
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