Question

我知道如何找到一个包含两个数组相同元素的数组，即

let resultArray = firstArray.filter(secondArray.contains)

但如果firstArray和secondArray都是CGPoint数组，如何在两者中找到包含相同x值的元素？

Answer 1

如果您不想分配持有CGPoint点x的额外secondArray数组，您可以使用以下备选方案

let resultAlt1 = firstArray
    .filter { pt in secondArray.reduce(false) { $0 || $1.x == pt.x } }

reduce的短路可能无法明确地实现这一点，因此如果性能成为问题，另一种选择是

let resultAlt2 = firstArray.filter {
    for pt in secondArray {
        if pt.x == $0.x { return true }
    }
    return false
}

这实质上与使用contains的其他答案相同，但不需要中间x点数组。

Answer 2

//your data
let search = [CGPoint(x: 0, y: 1), CGPoint(x: 1, y: 1), CGPoint(x: 0, y: 2), CGPoint(x: 3, y: 3)]
let queryPoints = [CGPoint(x: 0, y: 1), CGPoint(x: 1, y: 1)]

//actual search
let queryX = queryPoints.map{ $0.x }
let result = search.filter{ queryX.contains($0.x) }

Answer 3

let secoundArrayXPoints = secondArray.map{$0.x}
let resultArray = firstArray.filter{ secoundArrayXPoints.contains($0.x) }

Answer 4

let arrA: [CGPoint] = [CGPoint(x: 10, y: 10), CGPoint(x:15, y: 20), CGPoint(x: 20, y: 20)]

let arrB: [CGPoint] = [CGPoint(x: 10, y: 30), CGPoint(x:40, y: 20), CGPoint(x: 20, y: 30)]


let arrAx = arrA.map({ $0.x })


let arrC = arrB.filter({arrAx.contains($0.x) } )

从包含相同x值的两个CGPoint阵列中查找元素

4 个答案: