Python 定义一个完整的 vector 类

第一版：

# BEGIN VECTOR_V1
from array import array
import reprlib
import mathclass Vector:typecode = 'd'def __init__(self, components):self._components = array(self.typecode, components)  # <1>def __iter__(self):return iter(self._components)  # <2>def __repr__(self):components = reprlib.repr(self._components)  # <3>components = components[components.find('['):-1]  # <4>return 'Vector({})'.format(components)def __str__(self):return str(tuple(self))def __bytes__(self):return (bytes([ord(self.typecode)]) +bytes(self._components))  # <5>def __eq__(self, other):return tuple(self) == tuple(other)def __abs__(self):return math.sqrt(sum(x * x for x in self))  # <6>def __bool__(self):return bool(abs(self))@classmethoddef frombytes(cls, octets):typecode = chr(octets[0])memv = memoryview(octets[1:]).cast(typecode)return cls(memv)  # <7>
# END VECTOR_V1

第二版：可切片的序列

from array import array
import reprlib
import math
import numbersclass Vector:typecode = 'd'def __init__(self, components):self._components = array(self.typecode, components)def __iter__(self):return iter(self._components)def __repr__(self):components = reprlib.repr(self._components)components = components[components.find('['):-1]return 'Vector({})'.format(components)def __str__(self):return str(tuple(self))def __bytes__(self):return (bytes([ord(self.typecode)]) +bytes(self._components))def __eq__(self, other):return tuple(self) == tuple(other)def __abs__(self):return math.sqrt(sum(x * x for x in self))def __bool__(self):return bool(abs(self))# BEGIN VECTOR_V2def __len__(self):return len(self._components)def __getitem__(self, index):cls = type(self)  # <1>if isinstance(index, slice):  # <2>return cls(self._components[index])  # <3>elif isinstance(index, numbers.Integral):  # <4>return self._components[index]  # <5>else:msg = '{cls.__name__} indices must be integers'raise TypeError(msg.format(cls=cls))  # <6>
# END VECTOR_V2@classmethoddef frombytes(cls, octets):typecode = chr(octets[0])memv = memoryview(octets[1:]).cast(typecode)return cls(memv)

V2中最大的变化在于实现 __len__ 和 __getitem__ 从而实现了切片功能，这两个方法也是 vector 表现为序列所必需的

若使用 [1:4]，返回的是 slice ，slice 是内置的类型，通过审查 slice ，发现它有 start,stop和step 数据属性，以及 indices 方法。indices 中，给定长度为 len 的序列，计算 s 标识的扩展切片的起始和结束索引，以及步幅，超过边界的索引会被截掉。

Vector 第三版：动态存取属性

from array import array
import reprlib
import math
import numbersclass Vector:typecode = 'd'def __init__(self, components):self._components = array(self.typecode, components)def __iter__(self):return iter(self._components)def __repr__(self):components = reprlib.repr(self._components)components = components[components.find('['):-1]return 'Vector({})'.format(components)def __str__(self):return str(tuple(self))def __bytes__(self):return (bytes([ord(self.typecode)]) +bytes(self._components))def __eq__(self, other):return tuple(self) == tuple(other)def __abs__(self):return math.sqrt(sum(x * x for x in self))def __bool__(self):return bool(abs(self))def __len__(self):return len(self._components)def __getitem__(self, index):cls = type(self)if isinstance(index, slice):return cls(self._components[index])elif isinstance(index, numbers.Integral):return self._components[index]else:msg = '{.__name__} indices must be integers'raise TypeError(msg.format(cls))# BEGIN VECTOR_V3_GETATTRshortcut_names = 'xyzt'def __getattr__(self, name):cls = type(self)  # <1>if len(name) == 1:  # <2>pos = cls.shortcut_names.find(name)  # <3>if 0 <= pos < len(self._components):  # <4>return self._components[pos]msg = '{.__name__!r} object has no attribute {!r}'  # <5>raise AttributeError(msg.format(cls, name))
# END VECTOR_V3_GETATTR# BEGIN VECTOR_V3_SETATTRdef __setattr__(self, name, value):cls = type(self)if len(name) == 1:  # <1>if name in cls.shortcut_names:  # <2>error = 'readonly attribute {attr_name!r}'elif name.islower():  # <3>error = "can't set attributes 'a' to 'z' in {cls_name!r}"else:error = ''  # <4>if error:  # <5>msg = error.format(cls_name=cls.__name__, attr_name=name)raise AttributeError(msg)super().__setattr__(name, value)  # <6># END VECTOR_V3_SETATTR@classmethoddef frombytes(cls, octets):typecode = chr(octets[0])memv = memoryview(octets[1:]).cast(typecode)return cls(memv)

__getattr__ 和 __setattr__ ,前者是为了获取 vector 分量，后者是对已有分量的保护，v.x 不可以直接赋值，因为 x已经成为v的属性了，v.x 的值改变了，但是v的值未改变。

Vector 第四版：散列和快速等值测试

from array import array
import reprlib
import math
import numbers
import functools
import operatorclass Vector:typecode = 'd'def __init__(self, components):self._components = array(self.typecode, components)def __iter__(self):return iter(self._components)def __repr__(self):components = reprlib.repr(self._components)components = components[components.find('['):-1]return 'Vector({})'.format(components)def __str__(self):return str(tuple(self))def __bytes__(self):return (bytes([ord(self.typecode)]) +bytes(self._components))def __eq__(self, other):return (len(self) == len(other) andall(a == b for a, b in zip(self, other)))def __hash__(self):hashes = (hash(x) for x in self)return functools.reduce(operator.xor, hashes, 0)def __abs__(self):return math.sqrt(sum(x * x for x in self))def __bool__(self):return bool(abs(self))def __len__(self):return len(self._components)def __getitem__(self, index):cls = type(self)if isinstance(index, slice):return cls(self._components[index])elif isinstance(index, numbers.Integral):return self._components[index]else:msg = '{cls.__name__} indices must be integers'raise TypeError(msg.format(cls=cls))shortcut_names = 'xyzt'def __getattr__(self, name):cls = type(self)if len(name) == 1:pos = cls.shortcut_names.find(name)if 0 <= pos < len(self._components):return self._components[pos]msg = '{.__name__!r} object has no attribute {!r}'raise AttributeError(msg.format(cls, name))@classmethoddef frombytes(cls, octets):typecode = chr(octets[0])memv = memoryview(octets[1:]).cast(typecode)return cls(memv)

第五版：格式化

# BEGIN VECTOR_V5
"""
A multi-dimensional ``Vector`` class, take 5A ``Vector`` is built from an iterable of numbers::>>> Vector([3.1, 4.2])Vector([3.1, 4.2])>>> Vector((3, 4, 5))Vector([3.0, 4.0, 5.0])>>> Vector(range(10))Vector([0.0, 1.0, 2.0, 3.0, 4.0, ...])Tests with 2-dimensions (same results as ``vector2d_v1.py``)::>>> v1 = Vector([3, 4])>>> x, y = v1>>> x, y(3.0, 4.0)>>> v1Vector([3.0, 4.0])>>> v1_clone = eval(repr(v1))>>> v1 == v1_cloneTrue>>> print(v1)(3.0, 4.0)>>> octets = bytes(v1)>>> octetsb'd\\x00\\x00\\x00\\x00\\x00\\x00\\x08@\\x00\\x00\\x00\\x00\\x00\\x00\\x10@'>>> abs(v1)5.0>>> bool(v1), bool(Vector([0, 0]))(True, False)Test of ``.frombytes()`` class method:>>> v1_clone = Vector.frombytes(bytes(v1))>>> v1_cloneVector([3.0, 4.0])>>> v1 == v1_cloneTrueTests with 3-dimensions::>>> v1 = Vector([3, 4, 5])>>> x, y, z = v1>>> x, y, z(3.0, 4.0, 5.0)>>> v1Vector([3.0, 4.0, 5.0])>>> v1_clone = eval(repr(v1))>>> v1 == v1_cloneTrue>>> print(v1)(3.0, 4.0, 5.0)>>> abs(v1)  # doctest:+ELLIPSIS7.071067811...>>> bool(v1), bool(Vector([0, 0, 0]))(True, False)Tests with many dimensions::>>> v7 = Vector(range(7))>>> v7Vector([0.0, 1.0, 2.0, 3.0, 4.0, ...])>>> abs(v7)  # doctest:+ELLIPSIS9.53939201...Test of ``.__bytes__`` and ``.frombytes()`` methods::>>> v1 = Vector([3, 4, 5])>>> v1_clone = Vector.frombytes(bytes(v1))>>> v1_cloneVector([3.0, 4.0, 5.0])>>> v1 == v1_cloneTrueTests of sequence behavior::>>> v1 = Vector([3, 4, 5])>>> len(v1)3>>> v1[0], v1[len(v1)-1], v1[-1](3.0, 5.0, 5.0)Test of slicing::>>> v7 = Vector(range(7))>>> v7[-1]6.0>>> v7[1:4]Vector([1.0, 2.0, 3.0])>>> v7[-1:]Vector([6.0])>>> v7[1,2]Traceback (most recent call last):...TypeError: Vector indices must be integersTests of dynamic attribute access::>>> v7 = Vector(range(10))>>> v7.x0.0>>> v7.y, v7.z, v7.t(1.0, 2.0, 3.0)Dynamic attribute lookup failures::>>> v7.kTraceback (most recent call last):...AttributeError: 'Vector' object has no attribute 'k'>>> v3 = Vector(range(3))>>> v3.tTraceback (most recent call last):...AttributeError: 'Vector' object has no attribute 't'>>> v3.spamTraceback (most recent call last):...AttributeError: 'Vector' object has no attribute 'spam'Tests of hashing::>>> v1 = Vector([3, 4])>>> v2 = Vector([3.1, 4.2])>>> v3 = Vector([3, 4, 5])>>> v6 = Vector(range(6))>>> hash(v1), hash(v3), hash(v6)(7, 2, 1)Most hash values of non-integers vary from a 32-bit to 64-bit CPython build::>>> import sys>>> hash(v2) == (384307168202284039 if sys.maxsize > 2**32 else 357915986)TrueTests of ``format()`` with Cartesian coordinates in 2D::>>> v1 = Vector([3, 4])>>> format(v1)'(3.0, 4.0)'>>> format(v1, '.2f')'(3.00, 4.00)'>>> format(v1, '.3e')'(3.000e+00, 4.000e+00)'Tests of ``format()`` with Cartesian coordinates in 3D and 7D::>>> v3 = Vector([3, 4, 5])>>> format(v3)'(3.0, 4.0, 5.0)'>>> format(Vector(range(7)))'(0.0, 1.0, 2.0, 3.0, 4.0, 5.0, 6.0)'Tests of ``format()`` with spherical coordinates in 2D, 3D and 4D::>>> format(Vector([1, 1]), 'h')  # doctest:+ELLIPSIS'<1.414213..., 0.785398...>'>>> format(Vector([1, 1]), '.3eh')'<1.414e+00, 7.854e-01>'>>> format(Vector([1, 1]), '0.5fh')'<1.41421, 0.78540>'>>> format(Vector([1, 1, 1]), 'h')  # doctest:+ELLIPSIS'<1.73205..., 0.95531..., 0.78539...>'>>> format(Vector([2, 2, 2]), '.3eh')'<3.464e+00, 9.553e-01, 7.854e-01>'>>> format(Vector([0, 0, 0]), '0.5fh')'<0.00000, 0.00000, 0.00000>'>>> format(Vector([-1, -1, -1, -1]), 'h')  # doctest:+ELLIPSIS'<2.0, 2.09439..., 2.18627..., 3.92699...>'>>> format(Vector([2, 2, 2, 2]), '.3eh')'<4.000e+00, 1.047e+00, 9.553e-01, 7.854e-01>'>>> format(Vector([0, 1, 0, 0]), '0.5fh')'<1.00000, 1.57080, 0.00000, 0.00000>'
"""from array import array
import reprlib
import math
import numbers
import functools
import operator
import itertools  # <1>class Vector:typecode = 'd'def __init__(self, components):self._components = array(self.typecode, components)def __iter__(self):return iter(self._components)def __repr__(self):components = reprlib.repr(self._components)components = components[components.find('['):-1]return 'Vector({})'.format(components)def __str__(self):return str(tuple(self))def __bytes__(self):return (bytes([ord(self.typecode)]) +bytes(self._components))def __eq__(self, other):return (len(self) == len(other) andall(a == b for a, b in zip(self, other)))def __hash__(self):hashes = (hash(x) for x in self)return functools.reduce(operator.xor, hashes, 0)def __abs__(self):return math.sqrt(sum(x * x for x in self))def __bool__(self):return bool(abs(self))def __len__(self):return len(self._components)def __getitem__(self, index):cls = type(self)if isinstance(index, slice):return cls(self._components[index])elif isinstance(index, numbers.Integral):return self._components[index]else:msg = '{.__name__} indices must be integers'raise TypeError(msg.format(cls))shortcut_names = 'xyzt'def __getattr__(self, name):cls = type(self)if len(name) == 1:pos = cls.shortcut_names.find(name)if 0 <= pos < len(self._components):return self._components[pos]msg = '{.__name__!r} object has no attribute {!r}'raise AttributeError(msg.format(cls, name))def angle(self, n):  # <2>r = math.sqrt(sum(x * x for x in self[n:]))a = math.atan2(r, self[n-1])if (n == len(self) - 1) and (self[-1] < 0):return math.pi * 2 - aelse:return adef angles(self):  # <3>return (self.angle(n) for n in range(1, len(self)))def __format__(self, fmt_spec=''):if fmt_spec.endswith('h'):  # hyperspherical coordinatesfmt_spec = fmt_spec[:-1]coords = itertools.chain([abs(self)],self.angles())  # <4>outer_fmt = '<{}>'  # <5>else:coords = selfouter_fmt = '({})'  # <6>components = (format(c, fmt_spec) for c in coords)  # <7>return outer_fmt.format(', '.join(components))  # <8>@classmethoddef frombytes(cls, octets):typecode = chr(octets[0])memv = memoryview(octets[1:]).cast(typecode)return cls(memv)
# END VECTOR_V5

Python 定义一个完整的 vector 类相关推荐

python定义一个学生饭卡类_饭卡
前段时间买的破破烂烂的多普达CHT9000忽然出现了频繁找不到信号的现象,昨天下午还是断断续续的出现这种情况,到了今天变成断断续续地出现有信号的情况,倍感郁闷. 思考导致这种问题的原因,前两天刷了两次 ...
python定义一个dog类类属性有名字毛色体重_面向对象实践,练习,Python
1.定义一个汽车类(Car),属性有颜色,品牌,车牌号,并实例化两个对象 2.定义一个球员类(Player),属性有身高.体重.姓名,实例化两个球员,分别是姚明和科比 3.定义一个僵尸类(Zombie ...
python自己做个定时器_技术图文：如何利用 Python 做一个简单的定时器类？
原标题:技术图文:如何利用 Python 做一个简单的定时器类? 背景今天在B站上看有关 Python 最火的一个教学视频 -- "零基础入门学习 Python",这也是我们 P ...
python定义一个空数组_python数组 1_python 数组最后一个元素_python定义一个空数组 - 云+社区 - 腾讯云...
广告关闭腾讯云11.11云上盛惠 ,精选热门产品助力上云,云服务器首年88元起,买的越多返的越多,最高返5000元! 感悟: 1.python列表操作里不允许变量类型的指针2.case1类似于冒泡排 ...
定义一个Teacher（教师)类,和一个Student(学生)类
定义一个Teacher(教师)类,和一个Student(学生)类,二者有一部分数据成员是相同的,例如num(号码),name(姓名),sex(性别).编写程序,将一个Student对象转换为Teac ...
java定义一个学生类cstudent_编写一个JAVA程序片断定义一个表示学生的类student
编写一个JAVA程序片断定义一个表示学生的类student,包括域"学号","班级","姓名","性别","年 ...
Java编写学生类student程序_编写一个JAVA程序片断定义一个表示学生的类student.docx...
编写一个JAVA程序片断定义一个表示学生的类student,包括域"学号","班级","姓名","性别"," ...
实验3.2 定义一个简单的Computer类
题目定义一个简单的Computer类,有数据成员芯片(cpu).内存(ram).光驱(cdrom)等等,有两个公有成员函数run.stop.cpu为CPU类的一个对象,ram为RAM类的一个对象,c ...
学号java_java ---- 定义一个表示学生的类包括域“学号”、“班号”、“姓名”、“年龄”；...
1.编写一个JAVA类程序片段,定义一个表示学生的类student,包括域"学号"."班号"."姓名"."年龄":方法& ...

Python 定义一个完整的 vector 类

Python 定义一个完整的 vector 类相关推荐

最新文章

热门文章