第60行,在make_tuple中返回元组(l)TypeError:iter()返回类型为'Vector'的非迭代器

Question

我是Vector和制作课程的新手.我正在尝试构建自己的vector类,但是当我通过我的代码传递它时:

position + = heading*distance_moved

其中position和heading都是向量.标题是标准化的.我的目标是重复我的代码,直到position = destination.这堂课怎么了？

导入数学

class Vector(object):
    #defaults are set at 0.0 for x and y
    def __init__(self, x=0.0, y=0.0):
        self.x = x
        self.y = y

    #allows us to return a string for print
    def __str__(self):
        return "(%s, %s)"%(self.x, self.y)

    # from_points generates a vector between 2 pairs of (x,y) coordinates
    @classmethod
    def from_points(cls, P1, P2):
        return cls(P2[0] - P1[0], P2[1] - P1[1])

    #calculate magnitude(distance of the line from points a to points b
    def get_magnitude(self):
        return math.sqrt(self.x**2+self.y**2)

    #normalizes the vector (divides it by a magnitude and finds the direction)
    def normalize(self):
        magnitude = self.get_magnitude()
        self.x/= magnitude
        self.y/= magnitude

    #adds two vectors and returns the results(a new line from start of line ab to end of line bc)
    def __add__(self, rhs):
        return Vector(self.x +rhs.x, self.y+rhs.y)

    #subtracts two vectors
    def __sub__(self, rhs):
        return Vector(self.x - rhs.x, self.y-rhs.y)

    #negates or returns a vector back in the opposite direction
    def __neg__(self):
        return Vector(-self.x, -self.y)

    #multiply the vector (scales its size) multiplying by negative reverses the direction
    def __mul__(self, scalar):
        return Vector(self.x*scalar, self.y*scalar)

    #divides the vector (scales its size down)
    def __div__(self, scalar):
        return Vector(self.x/scalar, self.y/scalar)

    #iterator
    def __iter__(self):
        return self

    #next
    def next(self):
        self.current += 1
        return self.current - 1

    #turns a list into a tuple
    def make_tuple(l):
        return tuple(l)

Answer 1

我猜你使用的是python 3.x,因为我有类似的错误.我也是上课的新手,但分享我学到的东西会很高兴:)

在3.x中,使用__next__()而不是next()在类的定义中.在我的代码中重命名后没有发生错误,但是我遇到了另一个问题,"'Vector'对象没有属性'current'":)

我认为你可能更好地理解迭代器(和类？).最简单的例子是:

class Count:
    def __init__(self, n):
        self.max = n

    def __iter__(self):
        self.count = 0
        return self

    def __next__(self):
        if self.count == self.max:
            raise StopIteration
        self.count += 1
        return self.count - 1

if __name__ == '__main__':
    c = Count(4)
    for i in c:
        print(i, end = ',')

输出为0,1,2,3,.

使用vector类,我想迭代向量的组件.所以:

def __iter__(self):
    self.count = 0
    self.list = [self.x, self.y, self.z]  # for three dimension
    return self

def __next__(self):
    if self.count == len(self.list):
        raise StopIteration
    self.count += 1
    return self.list[self.count - 1]

并且迭代器输出序列x,y,z.

请注意,迭代器最重要的特性是逐步给出序列而不创建整个列表.因此,self.list如果序列非常长,那么制作它并不是一个好主意.更多细节在这里:python教程

Answer 2

传入的第一个参数make_tuple是您的实例（它与您在任何地方放置的参数Vector相同）。self

您必须传入要转换为元组的内容，这可能是您的 x 和 y 坐标：

def make_tuple(self):
    return (self.x, self.y)