ios 如何比较两个对象数组？
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How to compare two array of objects?
提问by Quang Hà
I have a class A:
我有一个A类：
class A {
var identifier: String?
var quantity: Int = 0
}
Two arrays of A instances:
A 实例的两个数组：
var array1: [A] = [a1, a2, a3, a4]
var array2: [A] = [a5, a6, a7, a8]
I don't know which is the best way to check:
array1==array2 if a1.identifier == a5.identifier, a2.identifier == a6.identifier, a3.identifier==a7.identifier, a4.identifier==a8.identifierin Swift.
我不知道哪种检查方式最好：
array1==array2 if a1.identifier == a5.identifier, a2.identifier == a6.identifier, a3.identifier==a7.identifier, a4.identifier==a8.identifier在 Swift 中。
Please help me...
请帮我...
回答by Rahul Tripathi
You can try like this:
你可以这样试试：
let result = zip(array1, array2).enumerated().filter() {
.0 == .1
}.map{struct Person
{
let name: String
let id: Int
}
var people1 = [
Person(name: "Quang Hà", id: 42),
Person(name: "Ly H?i", id: 23),
Person(name: "Maria", id: 99)
]
var people2 = [
Person(name: "Maria yyy", id: 99),
Person(name: "Billy", id: 42),
Person(name: "David", id: 23)
]
.0}
回答by t4nhpt
Assume your data like that:
假设你的数据是这样的：
func areArrayPeopleEqual(people1:[Person], people2: [Person]) -> Bool {
var array1 = people1
var array2 = people2
// Don't equal size => false
if array1.count != array2.count {
return false
}
// sort two arrays
array1.sortInPlace() { extension A: Equatable {
static func ==(lhs: A, rhs: A) -> Bool {
// Using "identifier" property for comparison
return lhs.identifier == rhs.identifier
}
}
.id > .id }
array2.sortInPlace() {let lhsArray = array1.sorted(by: { let isEqual = lhsArray == rhsArray
.identifier < .identifier })
let rhsArray = array2.sorted(by: { let isEqual = lhsArray.elementsEqual(rhsArray, by: { lhsArray.elementsEqual(rhsArray, by: { class A {
var identifier: String?
var quantity: Int = 0
init(identifier: String, quantity: Int) {
self.identifier = identifier
self.quantity = quantity
}
}
let a1: A = A(identifier: "1", quantity: 1)
let a2: A = A(identifier: "2", quantity: 2)
let a3: A = A(identifier: "3", quantity: 3)
let a4: A = A(identifier: "4", quantity: 4)
let a5: A = A(identifier: "1", quantity: 1)
let a6: A = A(identifier: "2", quantity: 2)
let a7: A = A(identifier: "3", quantity: 3)
let a8: A = A(identifier: "4", quantity: 4)
var array1: [A] = [a1, a2, a3, a4]
var array2: [A] = [a5, a6, a7, a8]
func areEquals(array1: [A], array2: [A]) -> Bool {
if array1.count < array2.count {
return false
}
for i in 0...array2.count - 1 {
if array1[i] != array2[i] {
return false
}
}
return true
}
extension A: Equatable {
static func ==(lhs: A, rhs: A) -> Bool {
//you can choose how and when they should be equals
return lhs.identifier == rhs.identifier
}
}
.identifier == .identifier })
== } )
.identifier < .identifier })
.id > .id }
// get count of the matched items
let result = zip(array1, array2).enumerate().filter() {
.0.id == .1.id
}.count
if result == array1.count {
return true
}
return false
}
This is the method to compare two arrays of people with id:
这是比较两个具有 id 的人数组的方法：
func toDictionary<E, K, V>(
array: [E],
transformer: (element: E) -> (key: K, value: V)?)
-> Dictionary<K, V>
{
return array.reduce([:]) {
(var dict, e) in
if let (key, value) = transformer(element: e)
{
dict[key] = value
}
return dict
}
}
回答by Anand
Swift 4
斯威夫特 4
The following method makes it much more easy.
下面的方法使它更容易。
Method 1 - Using Equatable Protocol
方法 1 - 使用 Equatable 协议
Step1 - Make your class 'A' equatable as follows
步骤 1 - 使您的类“A”相等，如下所示
let areEqual = array1.count == array2.count;
if areEqual {
let dict1 = toDictionary(array1) { (extension Array where Element: Hashable {
func difference(from other: [Element]) -> [Element] {
let thisSet = Set(self)
let otherSet = Set(other)
return Array(thisSet.symmetricDifference(otherSet))
}
}
let names1 = ["a1", "A4", "a3", "a4"]//["John", "Paul", "Ringo"]
let names2 = ["a1", "a5", "a4","a1.1"]//["Ringo", "George"]
let difference = names1.difference(from: names2)
.identifier, ##代码##.quantity) }
let dict2 = toDictionary(array2) { (##代码##.identifier, ##代码##.quantity) }
areEqual = NSDictionary(dictionary: dict1).isEqualToDictionary(dict2)
}
print(areEqual)
Step2 - Sort your arrays in ascending or descending order
Step2 - 按升序或降序对数组进行排序
##代码##Step3 - Use == or elementsEqual comparison
Step3 - 使用 == 或 elementsEqual 比较
##代码##OR
或者
##代码##Method 2 (Without Equatable Protocol)
方法 2（无 Equatable 协议）
Step 1 - Sort Array as described in Method1, step 2
步骤 1 - 按照方法 1 步骤 2 中所述对数组进行排序
Step 2 - Use elementsEqual
第 2 步 - 使用 elementsEqual
##代码##Read more about Array Comparison here
回答by Andrea Miotto
First we extend Equatableclass, to have a DRYcode, than if the 2 arrays are always of the same size, or if at least the first one is <= than the second you can go with this solution.
首先，我们扩展Equatable类，以获得DRY代码，而不是如果 2 个数组始终具有相同的大小，或者如果至少第一个是 <= 比第二个您可以使用此解决方案。
Pay attention that you are working with optionals, you may have to unwrap them before.
请注意，您正在使用可选项，您可能需要先打开它们。
##代码##
回答by ddb
回答by Jeremy Andrews
I found this really easy solution at https://www.hackingwithswift.com/example-code/language/how-to-find-the-difference-between-two-arrays
我在https://www.hackingwithswift.com/example-code/language/how-to-find-the-difference-between-two-arrays找到了这个非常简单的解决方案
##代码##