Question

我需要将SCNVector3与0.1相乘才能获得新职位。当我尝试执行此操作时，出现错误。以前在Xcode早期版本中，这是可行的。我将Xcode 10.1与Swift 4版本的编译器一起使用。对于相同类型的问题，我还看到了其他答案，但此处的数据类型不同。

import numpy as np
import math
import random
import operator

# Global variables
a = 0.1
b = 1


def function(x):
    return (math.sin(40*math.pi*x)+math.pow(x-1, 4))/(2*x)


def initial_pop():
    pop = np.random.uniform(a, b, 20)
    pop = pop.tolist()
    return pop


def moving_pop(population):
    # e c
    rand_item = population[random.randrange(len(population))]
    # print(rand_item)
    direction_arr = [-1, 1]
    direction = direction_arr[random.randrange(len(direction_arr))]
    # print(direction)
    new_element = rand_item + direction * np.random.normal(0, 0.2)
    if new_element > b:
        extra = new_element - b
        new_element = a + extra
    if new_element < a:
        extra = abs(new_element - a)
        new_element = b - extra
    # print(new_element)
    return new_element


def create_moved_pop(population):
    new_population = []
    for x in range(0, 20):
        new_element = moving_pop(population)
        new_population.append(new_element)
    # print(new_population)
    return new_population


def star_pop(population):
    random_item1 = population[random.randrange(len(population))]
    random_item2 = population[random.randrange(len(population))]
    while random_item2 == random_item1:
        random_item2 = population[random.randrange(len(population))]
    e_star = (random_item1 + random_item2)/2
    return e_star


def create_star_pop(population):
    star_population = []
    for x in range(0, 20):
        new_element = star_pop(population)
        star_population.append(new_element)
    # print(new_population)
    return star_population


pop = initial_pop()
print(pop)
for i in range(0, 500):
    moved_pop = create_moved_pop(pop)
    star_pop = create_star_pop(pop)
    pop_combined = sorted(sorted(pop) + sorted(moved_pop) +                 
sorted(star_pop))
    y_array = []
    for x in range(0, len(pop_combined)):
        y_array.append(function(pop_combined[x]))
    x_y_array = dict(zip(pop_combined, y_array))

    sorted_x_y_array = sorted(x_y_array.items(), key=operator.itemgetter(1), reverse=True)
    sorted_x_y_array = sorted_x_y_array[0:20]
    print(sorted_x_y_array)
    pop.clear()
    for x in sorted_x_y_array:
        pop.append(x[0])
    print(pop)

我正在使用的代码如下，

Binary operator '*' cannot be applied to operands of type 'SCNVector3' and 'Double'

让currentPosition = pointOfView.position +（dir * 0.1） ------> 在这里出现错误

   guard let pointOfView = sceneView.pointOfView else { return }

    let mat = pointOfView.transform
    let dir = SCNVector3(-1 * mat.m31, -1 * mat.m32, -1 * mat.m33)

Answer 1

未为操作数*和SCNVector3定义运算符Double。

我猜测someVector * 0.1是指将向量的每个分量乘以0.1？

在这种情况下，您可以定义自己的*运算符：

// put this in the global scope
func *(lhs: SCNVector3, rhs: Double) -> SCNVector3 {
    return SCNVector3(lhs.x * CGFloat(rhs), lhs.y * CGFloat(rhs), lhs.z * CGFloat(rhs))
}

// usage
SCNVector3(1, 2, 3) * 0.1 // (0.1, 0.2, 0.3)

Answer 2

将此拖放到您的项目中，它应该可以工作。

    public static func * (lhs: SCNVector3, rhs: Double) -> SCNVector3 {
        return SCNVector3(lhs.x * .init(rhs), lhs.y * .init(rhs), lhs.z * .init(rhs))
    }

    public static func * (lhs: Double, rhs: SCNVector3) -> SCNVector3 {
        return rhs * lhs
    }
}

二进制运算符'*'不能应用于'SCNVector3'和'Double'类型的操作数

2 个答案: