compat.swift

class Person {
    var id: Int
    var items: [String: Float]

    init(id: Int, items: [String: Float]) {
        self.id = id
        self.items = items
    }
}

var person1 = Person(id: 1, items: [:])
var person2 = Person(id: 2, items: [:])
var compatibilityItems = ["Cats", "Dogs", "Chamois"]

var currentPerson: Person?

currentPerson = person1
currentPerson?.items.updateValue(1, forKey: "Cats")
currentPerson?.items.updateValue(1, forKey: "Dogs")
currentPerson?.items.updateValue(1, forKey: "Chamois")
print(person1.items)

currentPerson = person2
currentPerson?.items.updateValue(1, forKey: "Cats")
currentPerson?.items.updateValue(1, forKey: "Dogs")
currentPerson?.items.updateValue(1, forKey: "Chamois")
print(person2.items)

// If diff 0.0 is 100% and 5.0 is 0%, calculate match percentage
var percentagesForAllItems: [Double] = []

for (key, person1Rating) in person1.items {
    let person2Rating = person2.items[key] ?? 0
    let difference = abs(person1Rating - person2Rating)/5.0
    percentagesForAllItems.append(Double(difference))
}
print(percentagesForAllItems)
let sumOfAllPercentages = percentagesForAllItems.reduce(0, +)
let matchPercentage = sumOfAllPercentages/Double(compatibilityItems.count)
//        print(matchPercentage, "%")
let matchString = 100 - (matchPercentage * 100).rounded()
print("\(matchString)%")