python走起之第三话

一. SET集合

set是一个无序且不重复的元素集

class set(object):
    """
    set() -> new empty set object
    set(iterable) -> new set object

    Build an unordered collection of unique elements.
    """
    def add(self, *args, **kwargs): # real signature unknown
        """ 添加 """
        """
        Add an element to a set.

        This has no effect if the element is already present.
        """
        pass

    def clear(self, *args, **kwargs): # real signature unknown
        """ Remove all elements from this set. """
        pass

    def copy(self, *args, **kwargs): # real signature unknown
        """ Return a shallow copy of a set. """
        pass

    def difference(self, *args, **kwargs): # real signature unknown
        """
        Return the difference of two or more sets as a new set.

        (i.e. all elements that are in this set but not the others.)
        """
        pass

    def difference_update(self, *args, **kwargs): # real signature unknown
        """ 删除当前set中的所有包含在 new set 里的元素 """
        """ Remove all elements of another set from this set. """
        pass

    def discard(self, *args, **kwargs): # real signature unknown
        """ 移除元素 """
        """
        Remove an element from a set if it is a member.

        If the element is not a member, do nothing.
        """
        pass

    def intersection(self, *args, **kwargs): # real signature unknown
        """ 取交集，新创建一个set """
        """
        Return the intersection of two or more sets as a new set.

        (i.e. elements that are common to all of the sets.)
        """
        pass

    def intersection_update(self, *args, **kwargs): # real signature unknown
        """ 取交集，修改原来set """
        """ Update a set with the intersection of itself and another. """
        pass

    def isdisjoint(self, *args, **kwargs): # real signature unknown
        """ 如果没有交集，返回true  """
        """ Return True if two sets have a null intersection. """
        pass

    def issubset(self, *args, **kwargs): # real signature unknown
        """ 是否是子集 """
        """ Report whether another set contains this set. """
        pass

    def issuperset(self, *args, **kwargs): # real signature unknown
        """ 是否是父集 """
        """ Report whether this set contains another set. """
        pass

    def pop(self, *args, **kwargs): # real signature unknown
        """ 移除 """
        """
        Remove and return an arbitrary set element.
        Raises KeyError if the set is empty.
        """
        pass

    def remove(self, *args, **kwargs): # real signature unknown
        """ 移除 """
        """
        Remove an element from a set; it must be a member.

        If the element is not a member, raise a KeyError.
        """
        pass

    def symmetric_difference(self, *args, **kwargs): # real signature unknown
        """ 差集，创建新对象"""
        """
        Return the symmetric difference of two sets as a new set.

        (i.e. all elements that are in exactly one of the sets.)
        """
        pass

    def symmetric_difference_update(self, *args, **kwargs): # real signature unknown
        """ 差集，改变原来 """
        """ Update a set with the symmetric difference of itself and another. """
        pass

    def union(self, *args, **kwargs): # real signature unknown
        """ 并集 """
        """
        Return the union of sets as a new set.

        (i.e. all elements that are in either set.)
        """
        pass

    def update(self, *args, **kwargs): # real signature unknown
        """ 更新 """
        """ Update a set with the union of itself and others. """
        pass

    def __and__(self, y): # real signature unknown; restored from __doc__
        """ x.__and__(y) <==> x&y """
        pass

    def __cmp__(self, y): # real signature unknown; restored from __doc__
        """ x.__cmp__(y) <==> cmp(x,y) """
        pass

    def __contains__(self, y): # real signature unknown; restored from __doc__
        """ x.__contains__(y) <==> y in x. """
        pass

    def __eq__(self, y): # real signature unknown; restored from __doc__
        """ x.__eq__(y) <==> x==y """
        pass

    def __getattribute__(self, name): # real signature unknown; restored from __doc__
        """ x.__getattribute__('name') <==> x.name """
        pass

    def __ge__(self, y): # real signature unknown; restored from __doc__
        """ x.__ge__(y) <==> x>=y """
        pass

    def __gt__(self, y): # real signature unknown; restored from __doc__
        """ x.__gt__(y) <==> x>y """
        pass

    def __iand__(self, y): # real signature unknown; restored from __doc__
        """ x.__iand__(y) <==> x&=y """
        pass

    def __init__(self, seq=()): # known special case of set.__init__
        """
        set() -> new empty set object
        set(iterable) -> new set object

        Build an unordered collection of unique elements.
        # (copied from class doc)
        """
        pass

    def __ior__(self, y): # real signature unknown; restored from __doc__
        """ x.__ior__(y) <==> x|=y """
        pass

    def __isub__(self, y): # real signature unknown; restored from __doc__
        """ x.__isub__(y) <==> x-=y """
        pass

    def __iter__(self): # real signature unknown; restored from __doc__
        """ x.__iter__() <==> iter(x) """
        pass

    def __ixor__(self, y): # real signature unknown; restored from __doc__
        """ x.__ixor__(y) <==> x^=y """
        pass

    def __len__(self): # real signature unknown; restored from __doc__
        """ x.__len__() <==> len(x) """
        pass

    def __le__(self, y): # real signature unknown; restored from __doc__
        """ x.__le__(y) <==> x<=y """
        pass

    def __lt__(self, y): # real signature unknown; restored from __doc__
        """ x.__lt__(y) <==> x<y """
        pass

    @staticmethod # known case of __new__
    def __new__(S, *more): # real signature unknown; restored from __doc__
        """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
        pass

    def __ne__(self, y): # real signature unknown; restored from __doc__
        """ x.__ne__(y) <==> x!=y """
        pass

    def __or__(self, y): # real signature unknown; restored from __doc__
        """ x.__or__(y) <==> x|y """
        pass

    def __rand__(self, y): # real signature unknown; restored from __doc__
        """ x.__rand__(y) <==> y&x """
        pass

    def __reduce__(self, *args, **kwargs): # real signature unknown
        """ Return state information for pickling. """
        pass

    def __repr__(self): # real signature unknown; restored from __doc__
        """ x.__repr__() <==> repr(x) """
        pass

    def __ror__(self, y): # real signature unknown; restored from __doc__
        """ x.__ror__(y) <==> y|x """
        pass

    def __rsub__(self, y): # real signature unknown; restored from __doc__
        """ x.__rsub__(y) <==> y-x """
        pass

    def __rxor__(self, y): # real signature unknown; restored from __doc__
        """ x.__rxor__(y) <==> y^x """
        pass

    def __sizeof__(self): # real signature unknown; restored from __doc__
        """ S.__sizeof__() -> size of S in memory, in bytes """
        pass

    def __sub__(self, y): # real signature unknown; restored from __doc__
        """ x.__sub__(y) <==> x-y """
        pass

    def __xor__(self, y): # real signature unknown; restored from __doc__
        """ x.__xor__(y) <==> x^y """
        pass

    __hash__ = None

set

Set

练习：寻找差异,打印出需要更新的、新增的、删除的

# 数据库中原有

old_dict = {

    "#1":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 },

    "#2":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 }

    "#3":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 }

}

 

# cmdb 新汇报的数据

new_dict = {

    "#1":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 800 },

    "#3":{ 'hostname':c1, 'cpu_count': 2, 'mem_capicity': 80 }

    "#4":{ 'hostname':c2, 'cpu_count': 2, 'mem_capicity': 80 }

}

 # 数据库中原有
 old_dict = {
     "#1":{ 'hostname':'1.1.1.1', 'cpu_count': 2, 'mem_capicity': 80 },
     "#2":{ 'hostname':'1.1.1.1', 'cpu_count': 2, 'mem_capicity': 80 },
     "#3":{ 'hostname':'1.1.1.1', 'cpu_count': 2, 'mem_capicity': 80 }
 }

 # cmdb 新汇报的数据
 new_dict = {
     "#1":{ 'hostname':'1.1.1.1', 'cpu_count': 2, 'mem_capicity': 800 },
     "#3":{ 'hostname':'1.1.1.1', 'cpu_count': 2, 'mem_capicity': 80 },
     "#4":{ 'hostname':'2.2.2.2', 'cpu_count': 2, 'mem_capicity': 80 }
 }

 old_set = set(old_dict.keys())
 update_list = list(old_set.intersection(new_dict.keys()))

 new_list = []
 del_list = []

 for i in new_dict.keys():
     if i not in update_list:
         new_list.append(i)

 for i in old_dict.keys():
     if i not in update_list:
         del_list.append(i)

 print(update_list,new_list,del_list)

 demo

二、深浅拷贝

对于 数字 和 字符串 而言，赋值、浅拷贝和深拷贝无意义，因为其永远指向同一个内存地址。

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

import copy # ######### 数字、字符串 ######### n1 = 123 # n1 = "i am alex age 10" print(id(n1)) # ## 赋值 ## n2 = n1 print(id(n2)) # ## 浅拷贝 ## n2 = copy.copy(n1) print(id(n2))   # ## 深拷贝 ## n3 = copy.deepcopy(n1) print(id(n3))

对于字典、元祖、列表 而言，进行赋值、浅拷贝和深拷贝时，其内存地址的变化是不同的。

赋值，只是创建一个变量，该变量指向原来内存地址，如：

1 2 3

n1 = {"k1": "wu", "k2": 123, "k3": ["alex", 456]}   n2 = n1

浅拷贝，在内存中只额外创建第一层数据

1 2 3 4 5

import copy   n1 = {"k1": "wu", "k2": 123, "k3": ["alex", 456]}   n3 = copy.copy(n1)

三、函数

在学习函数之前，一直遵循：面向过程编程，即：根据业务逻辑从上到下实现功能，其往往用一长段代码来实现指定功能，开发过程中最常见的操作就是粘贴复制，也就是将之前实现的代码块复制到现需功能处，如下：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

while True：     if cpu利用率 > 90%:         #发送邮件提醒         连接邮箱服务器         发送邮件         关闭连接         if 硬盘使用空间 > 90%:         #发送邮件提醒         连接邮箱服务器         发送邮件         关闭连接         if 内存占用 > 80%:         #发送邮件提醒         连接邮箱服务器         发送邮件         关闭连接

腚眼一看上述代码，if条件语句下的内容可以被提取出来公用，如下：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

def 发送邮件(内容)     #发送邮件提醒     连接邮箱服务器     发送邮件     关闭连接     while True：         if cpu利用率 > 90%:         发送邮件('CPU报警')         if 硬盘使用空间 > 90%:         发送邮件('硬盘报警')         if 内存占用 > 80%:

函数的定义主要有如下要点：

• def：表示函数的关键字
• 函数名：函数的名称，日后根据函数名调用函数
• 函数体：函数中进行一系列的逻辑计算，如：发送邮件、计算出 [11,22,38,888,2]中的最大数等...
• 参数：为函数体提供数据
• 返回值：当函数执行完毕后，可以给调用者返回数据。

以上要点中，比较重要有参数和返回值：

1、返回值

函数是一个功能块，该功能到底执行成功与否，需要通过返回值来告知调用者。

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18

def 发送短信():            发送短信的代码...        if 发送成功:         return True     else:         return False       while True:            # 每次执行发送短信函数，都会将返回值自动赋值给result     # 之后，可以根据result来写日志，或重发等操作        result = 发送短信()     if result == False:         记录日志，短信发送失败...

四、open函数

该函数用于文件处理，操作文件时，一般需要经历如下步骤：

• 打开文件
• 操作文件

1、打开文件

1	文件句柄 = open('文件路径', '模式')

打开文件时，需要指定文件路径和以何等方式打开文件，打开后，即可获取该文件句柄，日后通过此文件句柄对该文件操作。

打开文件的模式有：

• r，只读模式（默认）。
• w，只写模式。【不可读；不存在则创建；存在则删除内容；】
• a，追加模式。【可读；   不存在则创建；存在则只追加内容；】

"+" 表示可以同时读写某个文件

• r+，可读写文件。【可读；可写；可追加】
• w+，写读
• a+，同a

"U"表示在读取时，可以将 \r \n \r\n自动转换成 \n （与 r 或 r+ 模式同使用）

• rU
• r+U

"b"表示处理二进制文件（如：FTP发送上传ISO镜像文件，linux可忽略，windows处理二进制文件时需标注）

• rb
• wb
• ab