Python和数据结构学习 --- 0

好早前就想开始写了,可以一直懒没写.

书参考的是<Data Structures and Algorithms Using Python>基本是照着来.估计也会把里面的题目做做.

看完后打算看稍微难些的<Python Algorithms - Mastering Basic Algorithms in the Python Language>.

基本是自己的学习笔记.记录下而已.

扯了这么多蛋.开始.

首先第一个基本的结构是一维Array(后面还有多维的).它是个静态数组.可以迭代,获取设置值.

实现如下:

import ctypes
class Array:
    def __init__(self,size):
        assert size > 0,"Array size must be >0"
        self._size = size
        PyArrayType = ctypes.py_object * size
        self._elements = PyArrayType()
        self.clear(None)
    
    def __len__(self):
        return self._size
        
    def clear(self,value):
        for i in range(len(self)):
            self._elements[i] = value
            
    def __getitem__(self,index):
        assert index >= 0 and index < len(self),"Array subsctipt out of range"
        return self._elements[index]
    
    def __setitem__(self,index,value):
        assert index >= 0 and index < len(self),"Array subsctipt out of range"
        self._elements[index] = value
         
    
    def __iter__(self):
        return _ArrayIterator(self._elements)
    
class _ArrayIterator:
    def __init__(self,theArray):
        self._arrayRef = theArray
        self._curNdx = 0
    def __iter__(self):
        return self
    #注意这里提供的是next 而书中提供的是__next__它是对应这3版本中的
    def next(self):
        if self._curNdx < len(self._arrayRef):
            entry = self._arrayRef[self._curNdx]
            self._curNdx += 1
            return entry
        else:
            raise StopIteration

测试也很简单.

发现IPython超好,测试修改啥的都可以在一起.

当然了像Array这个数据结构可以直接使用list实现有2中方法,一是直接继承UserList,或者讲list作为内部元素.这里使用的第二中.

class Array:
    def __init__(self,size):
        self._size = size
        self._elements = [None]*size
        
    def __len__(self):
        return self._size
    
    def clear(self,value):
        for i in range(len(self)):
            self._elements[i] = value
    
    def __getitem__(self,index):
        return self._elements[index]
    
    def __setitem__(self,index,value):
        self._elements[index] = value
            
    def __iter__(self):
        return iter(self._elements)

好好了.明天搞二维的,睡觉先..