如何在3d空间中定义自定义的向量点类并计算其中心（平均）点？

Question

我正在制作一个制作形状之类的程序。我想通过查找面上存在的每个向量点的平均值来找到面的中心（由3d向量点列表提供）。 以下是我尝试过的：

import math

class vector:

    def __init__(self, x, y, z):

        self.x = x
        self.y = y
        self.z = z

class plane:

    def __init__(self, pointsList):

        self.vertex = []

        # check that each point is unique
        for p in range(0, len(pointsList)-1):


            for i in range(p+1, len(pointsList)):

                if (pointsList[p] != pointsList[i]):
                        if (i == len(pointsList)-1):
                            self.vertex.append(pointsList[p])

                else:
                    return None
        self.vertex.append(pointsList[-1])


    #returns the mean of x, y, and z            
    def center(self):

        xs = 0
        ys = 0
        zs = 0
        count = len(self.vertex)    

        for i in range(0, count):
            xs += self.vertex[i].x

            ys += self.vertex[i].y

            zs += self.vertex[i].z

        xMean = xs/count
        yMean = ys/count
        zMean = zs/count


        return vector(xMean, yMean, zMean)

然后我去测试函数平面。center（）：

#initialize some vectors
A = vector(1,7,5)
B = vector(3,9,4)
C = vector(0,1,0)
D = vector(0,0,0)

testList = [A, B, C, D]

#initialize a plane with those vectors
plane1 = plane(testList)

acenter = plane1.center()
print('%d %d %d' % (acenter.x, acenter.y, acenter.z))

然后返回的结果是1 4 2. 我想要x分量、y分量和z分量的平均值，但是4显然不是7, 9, 1, and 0的平均值。预期结果应该是1.0, 4.25, 2.25。我怎样才能做到这一点

Answer 1

谢谢大家。是的，我现在看到错误了。这件事很简单，我觉得很傻。我认为这与我的解释器默认使用python 2有关，但这显然远远不够

Answer 2

即使你自己解决了你的问题，我也会在这里付出我的两分钱。您可以使用Python的内置dataclass来构造vector。这将确保您不必制定手工规则来检查列表中的所有vectors是否唯一。您可以直接使用set函数来确保没有重复的向量（我已经重构了变量名以符合PEP8）

import math
from dataclasses import dataclass
from typing import Union

# using dataclass to build the vector class
# unsafe_hash = True makes the class hashable
@dataclass(unsafe_hash=True)
class Vector:
    x: Union[int, float]
    y: Union[int, float]
    z: Union[int, float]

现在让我们构建Plane类：

class Plane:
    def __init__(self, points_list):

        self.vertex = []
        self.points_list = points_list

    def _check_unique(self):
        """Check and make sure that there are no duplicate points in the list."""
        self.vertex = list(set(self.points_list))

        return self.vertex

    # returns the mean of x, y, and z
    def center(self):

        xs = 0
        ys = 0
        zs = 0

        vertex = self._check_unique()
        count = len(vertex)

        for i in range(0, count):
            xs += vertex[i].x

            ys += vertex[i].y

            zs += vertex[i].z

        x_mean = xs / count
        y_mean = ys / count
        z_mean = zs / count

        return Vector(x_mean, y_mean, z_mean)

现在让我们看看他们的行动：

# initialize some vectors
A = vector(1, 7, 5)
B = vector(3, 9, 4)
C = vector(0, 1, 0)
D = vector(0, 0, 0)

testList = [A, B, C, D, A, B]

# initialize a plane with those vectors
plane1 = plane(testList)

acenter = plane1.center()
print(f"{acenter.x}, {acenter.y}, {acenter.z}")

这将为您提供：

1.0, 4.25, 2.25