如何从数组中随机筛选和选择CGPoint

问题描述：

我有一些CGPoint数组，如下面的方法所示。我试图为我的精灵过滤一个位置，该位置按照所述顺序向下，向左，向上和向右循环移动。如何从数组中随机选择一个数组（向下，向左等），然后从所选数组中随机选择一个点，并记录数组，以便当再次调用该方法时，将使用以下组进行生成（遵循循环顺序）。例如，因为down是循环中的第一个，所以随机选择一个“向下数组”，如果说，选择down2，那么应该从down2随机选择一个点，比如p5。下一次调用此方法时，应遵循“左数组”等相同的过程。这似乎相当复杂。如何从数组中随机筛选和选择CGPoint

func nextPosition()->CGPoint { 
     let down1 = [p1, p2] 
     let down2 = [p3, p4, p5] 
     let left1 = [p6, p7] 
     let left2 = [p8, p9, p10] 
     let left3 = [p11, p12, p13] 
     let up1 = [p14, p15] 
     let up2 = [p16, p17] 
     let up3 = [p18, p19] 
     let right1 = [p20, p21] 
     let right2 = [p22, p23] 
     let right3 = [p24, p25] 
     let right4 = [p26, p27, p28, p29, p30] 

     //return point  
    }

答

这应该工作：

func nextPosition() -> CGPoint { 

    var pointsArray:[[CGPoint]] = [[]] 

    let down1 = [p1, p2] 
    pointsArray.append(down1) 
    let down2 = [p3, p4, p5] 
    pointsArray.append(down2) 

    let left1 = [p6, p7] 
    pointsArray.append(left1) 
    let left2 = [p8, p9, p10] 
    pointsArray.append(left2) 
    let left3 = [p11, p12, p13] 
    pointsArray.append(left3) 

    let up1 = [p14, p15] 
    pointsArray.append(up1) 
    let up2 = [p16, p17] 
    pointsArray.append(up2) 
    let up3 = [p18, p19] 
    pointsArray.append(up3) 

    let right1 = [p20, p21] 
    pointsArray.append(right1) 
    let right2 = [p22, p23] 
    pointsArray.append(right2) 
    let right3 = [p24, p25] 
    pointsArray.append(right3) 
    let right4 = [p26, p27, p28, p29, p30] 
    pointsArray.append(right4) 


    let randomDirection: Int = Int(arc4random_uniform(UInt32(pointsArray.count))) 
    let randomPoint: Int = Int(arc4random_uniform(UInt32(pointsArray[randomDirection].count))) 

    return pointsArray[randomDirection][randomPoint] 

}

我在做什么基本上是创建一个二维数组。第一个维度是针对方向的，第二个维度是针对该方向的。

追加第一个数组应该是'up1'而不是'up11'。会建议编辑，但它只有一个字符。 –

对不起，错字，我修好了。 –

此功能也适用于从每个单点中选择一个随机变量，但不会按顺序返回4个不同点（从下向上，向左，向上和向右）。 –

答

试试这个。函数的返回值是一个由4个CGPoint组成的数组 - 接下来的四个点，每个方向之一，即第一个是下降点，下一个是左边点等。函数返回的示例可以是[p3, p7, p19, p25]。

func nextPosition() -> [CGPoint] { 

    // Make a separate array for each group of points in each direction 
    let down1 = [p1, p2] 
    let down2 = [p3, p4, p5] 
    let left1 = [p6, p7] 
    let left2 = [p8, p9, p10] 
    let left3 = [p11, p12, p13] 
    let up1 = [p14, p15] 
    let up2 = [p16, p17] 
    let up3 = [p18, p19] 
    let right1 = [p20, p21] 
    let right2 = [p22, p23] 
    let right3 = [p24, p25] 
    let right4 = [p26, p27, p28, p29, p30] 

    // Make separate arrays for each direction which contains the previous arrays 
    let dArray = [down1, down2] 
    let lArray = [left1, left2, left3] 
    let uArray = [up1, up2, up3] 
    let rArray = [right1, right2, right3, right4] 

    // Make an array to group all the directions 
    let array = [dArray, lArray, uArray, rArray] 

    var nextPositions = [CGPoint]() 

    // loop through dArray, lArray etc. 
    for arr in array { 
     // pick random direction array 
     var length = UInt32(arr.count) 
     let random = Int(arc4random_uniform(length)) 

     // pick random point from sub array 
     length = UInt32(arr[random].count) 
     let random2 = Int(arc4random_uniform(length)) 

     // print final random point 
     print(arr[random][random2]) 
     nextPositions.append(arr[random][random2]) 
    } 
    return nextPositions 
}

如何从数组中随机筛选和选择CGPoint

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