python-L4_work

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http://f.dataguru.cn/thread-674423-1-1.html

import ctypes

import random

class Array(object):
def __init__(self, size):
"""
用传入的大小参数创建一个数组
:param size: int
"""
assert size > 0, "数组必须大于0"
self._size = size
# 用ctypes模块创建数组
py_array_type = ctypes.py_object * size
self._elements = py_array_type()
# Initialize each element
self.clear(None)

def __len__(self):
"""
返回数组的长度
:return: int
"""
return self._size

def __getitem__(self, index):
"""
返回索引的元素
:param index: int
:return: elements in Array
"""
assert 0 <= index < len(self), "数组下标越界。"
return self._elements[index]

def __setitem__(self, index, value):
"""
为索引的元素赋值
:param index: int
:param value: any type
"""
assert 0 <= index < len(self), "数组下标越界。"
self._elements[index] = value

def clear(self, value):
"""
将数组的每个元素设置为给定的值
:param value: any type
"""
for i in range(len(self)):
self._elements[i] = value

def __iter__(self):
"""
返回数组的迭代器
:return: iter
"""
return _ArrayIterator(self._elements)

def __str__(self):
"""
返回可打印数据
:return: str
"""
return str([element for element in self._elements])

class _ArrayIterator(object):
# 初始化类，下标指向第一位
def __init__(self, the_array):
"""
数组的迭代器类
:param the_array: Array
"""
self._arrayRef = the_array
self._curNdx = 0

def __iter__(self):
"""
返回迭代器本身
:return: iter
"""
return self

# 下标没有越界，返回对应元素，下标+1；下标越界，抛出StopIteration异常
def next(self):
"""
迭代器的next实现
:return: element of Array
"""
if self._curNdx < len(self._arrayRef):
entry = self._arrayRef[self._curNdx]
self._curNdx += 1
return entry
else:
raise StopIteration

class Vector(Array):
def __add__(self, other):
"""
向量加法，如果其中一个是int或float型，将向量的每一个元素与其相加，如果两个是Vector型，将两个向量中对应的元素相加
:param other: Vector or int or float
:return: Vector
"""
# 创建一个Vector类型的tmp变量
tmp = Vector(len(self))
# 判断other是否是int或float型
if isinstance(other, int) or isinstance(other, float):
# 将向量中每一个元素都加上other
for i in range(len(self)):
tmp[i] = self._elements[i] + other
# 判断other是否是Vector型
elif isinstance(other, Vector):
assert len(self) == len(other), '向量长度不相等'
# 将向量中每一个元素与other中对应元素相加
for i in range(len(self)):
tmp[i] = self._elements[i] + other[i]
# 如果other是其他类型，发起TypeError异常
else:
raise TypeError

return tmp

def __mul__(self, other):
"""
向量乘法，如果其中一个是int或float型，将向量的每一个元素与其相乘，如果两个是Vector型，将两个向量中对应的元素相乘
:param other: Vector or int or float
:return: Vector
"""
tmp = Vector(len(self))
if isinstance(other, int) or isinstance(other, float):
for i in range(len(self)):
tmp[i] = self._elements[i] * other

elif isinstance(other, Vector):
assert len(self) == len(other), '向量长度不相等'
for i in range(len(self)):
tmp[i] = self._elements[i] * other[i]
# 如果other是其他类型，发起TypeError异常
else:
raise TypeError
return tmp

def dot(self, other):
"""
计算向量点积，将两个向量对应元素相乘，并将结果相加
:param other: Vector
:return: Vector
"""
assert isinstance(other, Vector), '传入参数非Vector类型'
assert len(self) == len(other), '向量长度不相等'
sums = 0
for x, y in zip(self, other):
sums += x * y

return sums

if __name__ == '__main__':
x1 = Vector(4)
x1[0] = 1
x1[1] = 2
x1[2] = 3
x1[3] = 4

x2 = Vector(4)
x2[0] = 1
x2[1] = 2
x2[2] = 3
x2[3] = 4

print x1 + 4.5
print x1 + x2
print x1 * 3.4
print x1 * x2

print x1.dot(x2)

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