从CGPoints数组获取最大值和最小值 [英] Get the max and min values from an Array of CGPoints

问题描述

我们有一组CGPoints：

We have an array of CGPoints:

let points = [(1234.0, 1053.0), (1241.0, 1111.0), (1152.0, 1043.0)]

我想做的就是获得x最高的CGPoint值和数组中y值最高的那个。我将使用这些点来创建CGRect：

What I'm trying to do is get the CGPoint with the highest x value and the one with the highest y value in the array. I will be using these points to create a CGRect:

extension CGRect {
    init(p1: CGPoint, p2: CGPoint) {
        self.init(x: min(p1.x, p2.x),
                  y: min(p1.y, p2.y),
                  width: abs(p1.x - p2.x),
                  height: abs(p1.y - p2.y))
    }
}

我知道有一种方法可以通过以下操作获取数组中的最大值和最小值：

I know there a way to get max and min values in an array by doing something like this:

points.min()
points.max()

但是这些似乎不起作用，因为它包含CGPoints数组。可以从数组中获取这些值吗？

but these don't seem to work since its an array of CGPoints. Is it possible to get these values from the array?

推荐答案

您可以映射值以在x和y中找到最小值和最大值。坐标如下。如果不确定 points 数组是否包含任何数据，请使用guard语句以避免强制展开：

You can map values to find the min and max in x and y coordinates like below. If you're not sure if points array contains any data, use guard statement to avoid force unwrapping:

let xArray = points.map(\.x)
let yArray = points.map(\.y)
guard let minX = xArray.min(),
      let maxX = xArray.max(),
      let minY = yArray.min(),
      let maxY = yArray.max() else { return }

然后从那里：

let minPoint = CGPoint(x: minX, y: minY)
let maxPoint = CGPoint(x: minY, y: minY)

然后您可以修改扩展函数，因为您已经知道哪些值是最小值和最大值：

then you can modify your extension function because you already know which values are min and max:

extension CGRect {
    init(minPoint: CGPoint, maxPoint: CGPoint) {
        self.init(x: minPoint.x,
                  y: minPoint.y,
                  width: maxPoint.x - minPoint.x,
                  height: maxPoint.y - minPoint.y)
    }
}

正如Leo Dabus在下面的评论中建议的那样，您可以在失效的初始化程序扩展中一次性完成所有操作：

As Leo Dabus suggested in the comment below, you can do it all in one go inside failable initializer extension:

extension CGRect {
    init?(points: [CGPoint]) {
        let xArray = points.map(\.x)
        let yArray = points.map(\.y)
        if  let minX = xArray.min(),
            let maxX = xArray.max(),
            let minY = yArray.min(),
            let maxY = yArray.max() {

            self.init(x: minX,
                      y: minY,
                      width: maxX - minX,
                      height: maxY - minY)
        } else {
            return nil
        }
    }
}

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