arrays - Swift - 根据相同的特征对元素进行分组

Question

在 Swift 4 中，我有:

let customers = [Customer(name: "John", country: "US", profession: "Engineer"), Customer(name: "Mary", country: "UK", profession: "Nurse"), Customer(name: "Diana", country: "US", profession: "Engineer"), Customer(name: "Paul", country: "US", profession: "Plumber"), Customer(name: "Sam", country: "UK", profession: "Nurse")]

我想有一个函数可以过滤 customers 中的元素，这样每次其中至少 2 个元素的名称和职业相等时，它们就会被添加到一个此函数自动创建的数组:

var customers1 = [Customer(name: "John", country: "US", profession: "Engineer"), Customer(name: "Diana", country: "US", profession: "Engineer")]
var customers2 = [Customer(name: "Mary", country: "UK", profession: "Nurse"), Customer(name: "Sam", country: "UK", profession: "Nurse")]

我搜索没有成功，但是我选择了一些可能适用于这种情况的解决方案:

extension Array where Element: Comparable {
    func containsSameElements(as other: [Element]) -> Bool {
        return self[1] == other[1] && self[2] == other[2]
    }
}

或

func ==<Element : Equatable> (lhs: [[Element]], rhs: [[Element]]) -> Bool {
    return lhs.elementsEqual(rhs, by: ==)
}

或

elementsEqual()/contains() 带循环。

或

flatMap()/reduce()/filter() 的组合。

谢谢。

Answer 1

根据您的反馈和说明，我会做这样的事情。

struct CountryAndProfession: Hashable, CustomStringConvertible {

    let country: String
    let profession: String


    var description: String {
        return "CountryAndProfession{country: \(country), profession: \(profession)}"
    }

    var hashValue: Int {
        return "\(country)__\(profession)".hashValue
    }
    static func ==(left: CountryAndProfession, right: CountryAndProfession) -> Bool {
        return left.country == right.country && left.profession == right.profession
    }
}

// The Customer Type you apparently are dealing with. (May need a custom init depending on your use case
struct Customer: CustomStringConvertible {
    let name: String
    let countryAndProfession: CountryAndProfession

    var description: String {
        return "Customer{name: \(name), countryAndProfession: \(countryAndProfession)}"
    }

    // returns a dictionary with the passed customer's CountryAndProfession as the key, and the matching
    static func makeDictionaryWithCountryAndProfession(from customers: [Customer]) -> [CountryAndProfession : [Customer]] {
        var customersArrayDictionary: [CountryAndProfession : [Customer]] = [:]

        customers.forEach { (customer) in
            if customersArrayDictionary.keys.contains(customer.countryAndProfession) {
                customersArrayDictionary[customer.countryAndProfession]?.append(customer)
            }
            else {
                customersArrayDictionary[customer.countryAndProfession] = [customer]
            }
        }
        return customersArrayDictionary
    }

    static func getArraysBasedOnCountries(from customerArray: [Customer]) -> [[Customer]] {
        return Array(makeDictionaryWithCountryAndProfession(from: customerArray).values)
    }
}

let arrayOfArrays = [["John", "A", "A" ], ["Mary", "A", "B" ], ["Diana", "A", "A" ], ["Paul", "B", "B" ], ["Sam", "A", "B" ]]

//If you're dealing with non-predictable data, you should probably have some Optionality
let allCustomers = arrayOfArrays.map{ Customer(name: $0[0], countryAndProfession: CountryAndProfession(country: $0[1], profession: $0[2])) }

let splitCustomers = Customer.getArraysBasedOnCountries(from: allCustomers)
//contains [[John, Diana], [Mary, Sam], [Paul]]

我仍然不太确定您希望最终结果是什么样的(提出问题总是有帮助的)，但是您应该能够使用 获得您正在寻找的结果makeDictionaryWithCountryAndProfession 与您正在寻找或使用的特定 CountryAndProfession 相结合 .filter