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  • Python:初识Python(二)

    下载安装PyCharm

        pycharm 专业版(PyCharm是一种Python IDE,带有一整套可以帮助用户在使用Python语言开发时提高其效率的工具,比如调试、语法高亮、Project管理、代码跳转、智能提示、自动完成、单元测试、版本控制。此外,该IDE提供了一些高级功能,以用于支持Django框架下的专业Web开发。)

        注册之后可长期使用。

         

    编码关系:

    Python2.7

    unicode是万国码,utf-8是对万国码的一个精简,gbk类似utf-8。unicode可以转换成utf-8,转换过程叫编码(动词),utf-8转换成unicode的过程叫解码,gbk和unicode之间的转换同理。如果utf-8变成gbk就需要先解码再编码。如图:

    在写Python时,如果终端是gbk格式解码,而以utf-8格式输出,就会出现乱码。这时就需要把终端改成utf-8格式:

    示例:

    
    
    #!/usr/bin/env python
    # -*- coding:utf-8 -*-
    1 temp = "测试" #utf-8
    2 #解码,需要指定原来是什么编码
    3 temp_unicode = temp.decode('utf-8')
    4 #编码,需要指定要变成什么编码
    5 temp_gbk = temp_unicode.encode('gbk')
    6 print(temp_gbk)

     

    Python3.5

    py3是自动转换,通过utf-8转换成unicode,再转换成gbk。

    并且py3,移除了Python的unicode类型。

    #!/usr/bin/env python
    # -*- coding:utf-8 -*-
    1  temp = "测试" #utf-8
    2  temp_gbk = temp_unicode.encode('gbk')
    3  print(temp_gbk)

     

     

     

    • 运算符

     

    一、算数运算:

     

    二、比较运算:

     

    三、赋值运算:

     

    四、逻辑运算:

     

    and:
    True and True:只有and两边的条件都是True,返回的结果才是True,否则都是False.
     
    or:
    True or False:在or表达式中,两边只有一个为True,表达式才为True.
     
    not:
    非零即为真
    not False == True
    not True == False

                                                             。

    五、成员运算:

     示例:一和二的粒度不一样

    一:

    s = "name age"
    ret = "age" in s
    print(ret)
    #打印结果:True
    
    
    s = "name age"
    ret = "ge" in s
    print(ret)
    #打印结果:True
    
    ##########
    s = "name age"
    ret = "lage" in s
    print(ret)
    #打印结果:False

    二:

    li = ["name","age","test"]
    ret = "age" in li
    print(ret)
    #打印结果:True
    ##########
    li = ["name","age","test"]
    ret = "ge" in li
    print(ret)
    #打印结果:False
    • 基本数据类型

     py2.7中9除以2等于4,要想实现等于4.5就需要引入模块了。此时PyCharm就派上用场了,方便引入模块。

    一、数字

    int(整型)

        在32位机器上,整数的位数为32位,取值范围为-2**31~2**31-1,即-2147483648~2147483647

        在64位系统上,整数的位数为64位,取值范围为-2**63~2**63-1,即-92233720368547758089223372036854775807

    class int(object):
        """
        int(x=0) -> int or long
        int(x, base=10) -> int or long
        
        Convert a number or string to an integer, or return 0 if no arguments
        are given.  If x is floating point, the conversion truncates towards zero.
        If x is outside the integer range, the function returns a long instead.
        
        If x is not a number or if base is given, then x must be a string or
        Unicode object representing an integer literal in the given base.  The
        literal can be preceded by '+' or '-' and be surrounded by whitespace.
        The base defaults to 10.  Valid bases are 0 and 2-36.  Base 0 means to
        interpret the base from the string as an integer literal.
        >>> int('0b100', base=0)
        4
        """
        def bit_length(self): 
            """ 返回表示该数字的时占用的最少位数 """
            """
            int.bit_length() -> int
            
            Number of bits necessary to represent self in binary.
            >>> bin(37)
            '0b100101'
            >>> (37).bit_length()
            6
            """
            return 0
    
        def conjugate(self, *args, **kwargs): # real signature unknown
            """ 返回该复数的共轭复数 """
            """ Returns self, the complex conjugate of any int. """
            pass
    
        def __abs__(self):
            """ 返回绝对值 """
            """ x.__abs__() <==> abs(x) """
            pass
    
        def __add__(self, y):
            """ x.__add__(y) <==> x+y """
            pass
    
        def __and__(self, y):
            """ x.__and__(y) <==> x&y """
            pass
    
        def __cmp__(self, y): 
            """ 比较两个数大小 """
            """ x.__cmp__(y) <==> cmp(x,y) """
            pass
    
        def __coerce__(self, y):
            """ 强制生成一个元组 """ 
            """ x.__coerce__(y) <==> coerce(x, y) """
            pass
    
        def __divmod__(self, y): 
            """ 相除,得到商和余数组成的元组 """ 
            """ x.__divmod__(y) <==> divmod(x, y) """
            pass
    
        def __div__(self, y): 
            """ x.__div__(y) <==> x/y """
            pass
    
        def __float__(self): 
            """ 转换为浮点类型 """ 
            """ x.__float__() <==> float(x) """
            pass
    
        def __floordiv__(self, y): 
            """ x.__floordiv__(y) <==> x//y """
            pass
    
        def __format__(self, *args, **kwargs): # real signature unknown
            pass
    
        def __getattribute__(self, name): 
            """ x.__getattribute__('name') <==> x.name """
            pass
    
        def __getnewargs__(self, *args, **kwargs): # real signature unknown
            """ 内部调用 __new__方法或创建对象时传入参数使用 """ 
            pass
    
        def __hash__(self): 
            """如果对象object为哈希表类型,返回对象object的哈希值。哈希值为整数。在字典查找中,哈希值用于快速比较字典的键。两个数值如果相等,则哈希值也相等。"""
            """ x.__hash__() <==> hash(x) """
            pass
    
        def __hex__(self): 
            """ 返回当前数的 十六进制 表示 """ 
            """ x.__hex__() <==> hex(x) """
            pass
    
        def __index__(self): 
            """ 用于切片,数字无意义 """
            """ x[y:z] <==> x[y.__index__():z.__index__()] """
            pass
    
        def __init__(self, x, base=10): # known special case of int.__init__
            """ 构造方法,执行 x = 123 或 x = int(10) 时,自动调用,暂时忽略 """ 
            """
            int(x=0) -> int or long
            int(x, base=10) -> int or long
            
            Convert a number or string to an integer, or return 0 if no arguments
            are given.  If x is floating point, the conversion truncates towards zero.
            If x is outside the integer range, the function returns a long instead.
            
            If x is not a number or if base is given, then x must be a string or
            Unicode object representing an integer literal in the given base.  The
            literal can be preceded by '+' or '-' and be surrounded by whitespace.
            The base defaults to 10.  Valid bases are 0 and 2-36.  Base 0 means to
            interpret the base from the string as an integer literal.
            >>> int('0b100', base=0)
            4
            # (copied from class doc)
            """
            pass
    
        def __int__(self): 
            """ 转换为整数 """ 
            """ x.__int__() <==> int(x) """
            pass
    
        def __invert__(self): 
            """ x.__invert__() <==> ~x """
            pass
    
        def __long__(self): 
            """ 转换为长整数 """ 
            """ x.__long__() <==> long(x) """
            pass
    
        def __lshift__(self, y): 
            """ x.__lshift__(y) <==> x<<y """
            pass
    
        def __mod__(self, y): 
            """ x.__mod__(y) <==> x%y """
            pass
    
        def __mul__(self, y): 
            """ x.__mul__(y) <==> x*y """
            pass
    
        def __neg__(self): 
            """ x.__neg__() <==> -x """
            pass
    
        @staticmethod # known case of __new__
        def __new__(S, *more): 
            """ T.__new__(S, ...) -> a new object with type S, a subtype of T """
            pass
    
        def __nonzero__(self): 
            """ x.__nonzero__() <==> x != 0 """
            pass
    
        def __oct__(self): 
            """ 返回改值的 八进制 表示 """ 
            """ x.__oct__() <==> oct(x) """
            pass
    
        def __or__(self, y): 
            """ x.__or__(y) <==> x|y """
            pass
    
        def __pos__(self): 
            """ x.__pos__() <==> +x """
            pass
    
        def __pow__(self, y, z=None): 
            """ 幂,次方 """ 
            """ x.__pow__(y[, z]) <==> pow(x, y[, z]) """
            pass
    
        def __radd__(self, y): 
            """ x.__radd__(y) <==> y+x """
            pass
    
        def __rand__(self, y): 
            """ x.__rand__(y) <==> y&x """
            pass
    
        def __rdivmod__(self, y): 
            """ x.__rdivmod__(y) <==> divmod(y, x) """
            pass
    
        def __rdiv__(self, y): 
            """ x.__rdiv__(y) <==> y/x """
            pass
    
        def __repr__(self): 
            """转化为解释器可读取的形式 """
            """ x.__repr__() <==> repr(x) """
            pass
    
        def __str__(self): 
            """转换为人阅读的形式,如果没有适于人阅读的解释形式的话,则返回解释器课阅读的形式"""
            """ x.__str__() <==> str(x) """
            pass
    
        def __rfloordiv__(self, y): 
            """ x.__rfloordiv__(y) <==> y//x """
            pass
    
        def __rlshift__(self, y): 
            """ x.__rlshift__(y) <==> y<<x """
            pass
    
        def __rmod__(self, y): 
            """ x.__rmod__(y) <==> y%x """
            pass
    
        def __rmul__(self, y): 
            """ x.__rmul__(y) <==> y*x """
            pass
    
        def __ror__(self, y): 
            """ x.__ror__(y) <==> y|x """
            pass
    
        def __rpow__(self, x, z=None): 
            """ y.__rpow__(x[, z]) <==> pow(x, y[, z]) """
            pass
    
        def __rrshift__(self, y): 
            """ x.__rrshift__(y) <==> y>>x """
            pass
    
        def __rshift__(self, y): 
            """ x.__rshift__(y) <==> x>>y """
            pass
    
        def __rsub__(self, y): 
            """ x.__rsub__(y) <==> y-x """
            pass
    
        def __rtruediv__(self, y): 
            """ x.__rtruediv__(y) <==> y/x """
            pass
    
        def __rxor__(self, y): 
            """ x.__rxor__(y) <==> y^x """
            pass
    
        def __sub__(self, y): 
            """ x.__sub__(y) <==> x-y """
            pass
    
        def __truediv__(self, y): 
            """ x.__truediv__(y) <==> x/y """
            pass
    
        def __trunc__(self, *args, **kwargs): 
            """ 返回数值被截取为整形的值,在整形中无意义 """
            pass
    
        def __xor__(self, y): 
            """ x.__xor__(y) <==> x^y """
            pass
    
        denominator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
        """ 分母 = 1 """
        """the denominator of a rational number in lowest terms"""
    
        imag = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
        """ 虚数,无意义 """
        """the imaginary part of a complex number"""
    
        numerator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
        """ 分子 = 数字大小 """
        """the numerator of a rational number in lowest terms"""
    
        real = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
        """ 实属,无意义 """
        """the real part of a complex number"""
    int

     

    二、布尔值

    真或假

    1 或 0

    非零即为真

     

    三、字符串

    字符串用单引号('')或者双引号("")来创建

    #!/usr/bin/env python
    # -*- coding:utf-8 -*-
    name = "zouqian"
    print(name)

     字符串常用功能:

    1.移除空白

    2.分割

    3.长度

    4.索引

    5.切片

    """
    capitalize()
    将字符串的首字母转换为大写
    """
    name = " zou qian zouqian"
    ret = name.capitalize()
    print(ret)
    """
    center(width, fillchar)
    返回一个指定的宽度 width 居中的字符串,fillchar 为填充的字符,默认为空格
    """
    ret = name.center(20,'*')
    print(ret)
    
    """
    count(str, beg= 0,end=len(string))
    显示某字符在开始beg到结束end中间出现的次数
    """
    ret = name.count('zo',0,15)
    print(ret)
    """
    decode(encoding='UTF-8',errors='strict')
    解码
    encode(encoding='UTF-8',errors='strict')
    以 encoding 指定的编码格式编码字符串
    
    temp = "测试"
    #解码,需要指定原来是什么编码
    temp_unicode = temp.decode('utf-8')
    #编码,需要指定要编成什么编码
    temp_gbk = temp_unicode.encode('gbk')
    print(temp_gbk)
    """
    """
    endswith(suffix, beg=0, end=len(string))
    检查字符串是否以某字符串结尾如果是,返回 True,否则返回 False.
    """
    ret = name.endswith('n')
    print(ret)
    """
    expandtabs(tabsize=8)
    	:表示tab键,默认为88个空格
    """
    ret = name.expandtabs()
    print(ret)
    """
    find(str, beg=0 end=len(string))
    检查“e”是否包含在指定范围内,如果是,会显示在第几位,如果不是就会提示-1
    """
    ret = name.find('e')
    print(ret)
    
    """
    
    """
    isdigit()
    是否是数字
    """
    ret = name.isdigit()
    print(ret)
    
    """
    lstrip()
    移除左侧空白
    """
    ret = name.lstrip()
    print(ret)
    
    """
    rstrip()
    移除右侧空白
    """
    ret = name.rstrip()
    print(ret)
    
    “““
    split
    分割
    ”””
    name = "hello,zouqian"
    ret = name.split(",")
    print(ret)
    
    """
    strip([chars])
    去除左右两边空格
    """
    ret = name.strip()
    print(ret)
    
    """
    title()
    标题格式
    """
    ret = value.title()
    print(ret)
    str

     

     

    四、列表

    列表中每个位置都下标从0开始的数字

    列表使用中括号:[]

    创建列表:

    #!/usr/bin/env python
    # -*- coding:utf-8 -*-
    list = ['a','b','c']

    基本操作:

    1.索引

    2.切片

    3.追加

    4.删除

    5.长度

    6.切片

    7.循环

    8.包含

     

     

    """
    append 追加
    """
    list = ['a','b','c']
    list.append('d')
    print(list)
    
    
    """
    count 统计某个元素出现的次数
    """
    list = [1,4,2,3,4,5,10,3,5,2,4,8,6]
    ret = list.count(5)
    print(ret)
    
    
    """
    extend 在列表最后追加另一个列表中的所有元素
    
    """
    list2 = [404,505,606]
    list.extend(list2)
    print(list)
    
    """
    pop 移除列表中的一个元素(默认最后一个元素)
    """
    num = [1,2,3,4,5,6]
    num.pop()
    print(num)
    
    
    """
    remove 移除列表中某个值
    """
    num = [1,2,3,4,5,6]
    num.remove(6)
    print(num)
    
    
    """
    clear 清空列表
    """
    list

     

    五、元祖

    元祖和列表是类似的,但是列表可以修改(增删改),元祖不能修改,只能查。

    元祖使用小括号:()

    基本操作:

    1.索引

    2.切片

    3.循环

    4.长度

    5.包含

    1 tuple  将列表转换为元祖
    2 list = ['a', 'b', 'c']
    3 temp = tuple(list)
    4 print(temp)

     

     

    六、字典(无序)

    字典使用花括号:{}。字典的每个键值(key=>value)对用冒号(:)分割,每个对之间用逗号(,)分割

    字典没办法切片,可以循环,默认只输出key,可以删除指定索引的键值对。

     

    常用操作:

    1.索引

    2.新增

    3.删除

    4.键.值.键值对

    5.循环

    6.长度

     

    class dict(object):
        """
        dict() -> new empty dictionary
        dict(mapping) -> new dictionary initialized from a mapping object's
            (key, value) pairs
        dict(iterable) -> new dictionary initialized as if via:
            d = {}
            for k, v in iterable:
                d[k] = v
        dict(**kwargs) -> new dictionary initialized with the name=value pairs
            in the keyword argument list.  For example:  dict(one=1, two=2)
        """
    
        def clear(self): # real signature unknown; restored from __doc__
            """ 清除内容 """
            """ D.clear() -> None.  Remove all items from D. """
            pass
    
        def copy(self): # real signature unknown; restored from __doc__
            """ 浅拷贝 """
            """ D.copy() -> a shallow copy of D """
            pass
    
        @staticmethod # known case
        def fromkeys(S, v=None): # real signature unknown; restored from __doc__
            """
            dict.fromkeys(S[,v]) -> New dict with keys from S and values equal to v.
            v defaults to None.
            """
            pass
    
        def get(self, k, d=None): # real signature unknown; restored from __doc__
            """ 根据key获取值,d是默认值 """
            """ D.get(k[,d]) -> D[k] if k in D, else d.  d defaults to None. """
            pass
    
        def has_key(self, k): # real signature unknown; restored from __doc__
            """ 是否有key """
            """ D.has_key(k) -> True if D has a key k, else False """
            return False
    
        def items(self): # real signature unknown; restored from __doc__
            """ 所有项的列表形式 """
            """ D.items() -> list of D's (key, value) pairs, as 2-tuples """
            return []
    
        def iteritems(self): # real signature unknown; restored from __doc__
            """ 项可迭代 """
            """ D.iteritems() -> an iterator over the (key, value) items of D """
            pass
    
        def iterkeys(self): # real signature unknown; restored from __doc__
            """ key可迭代 """
            """ D.iterkeys() -> an iterator over the keys of D """
            pass
    
        def itervalues(self): # real signature unknown; restored from __doc__
            """ value可迭代 """
            """ D.itervalues() -> an iterator over the values of D """
            pass
    
        def keys(self): # real signature unknown; restored from __doc__
            """ 所有的key列表 """
            """ D.keys() -> list of D's keys """
            return []
    
        def pop(self, k, d=None): # real signature unknown; restored from __doc__
            """ 获取并在字典中移除 """
            """
            D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
            If key is not found, d is returned if given, otherwise KeyError is raised
            """
            pass
    
        def popitem(self): # real signature unknown; restored from __doc__
            """ 获取并在字典中移除 """
            """
            D.popitem() -> (k, v), remove and return some (key, value) pair as a
            2-tuple; but raise KeyError if D is empty.
            """
            pass
    
        def setdefault(self, k, d=None): # real signature unknown; restored from __doc__
            """ 如果key不存在,则创建,如果存在,则返回已存在的值且不修改 """
            """ D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D """
            pass
    
        def update(self, E=None, **F): # known special case of dict.update
            """ 更新
                {'name':'alex', 'age': 18000}
                [('name','sbsbsb'),]
            """
            """
            D.update([E, ]**F) -> None.  Update D from dict/iterable E and F.
            If E present and has a .keys() method, does:     for k in E: D[k] = E[k]
            If E present and lacks .keys() method, does:     for (k, v) in E: D[k] = v
            In either case, this is followed by: for k in F: D[k] = F[k]
            """
            pass
    
        def values(self): # real signature unknown; restored from __doc__
            """ 所有的值 """
            """ D.values() -> list of D's values """
            return []
    
        def viewitems(self): # real signature unknown; restored from __doc__
            """ 所有项,只是将内容保存至view对象中 """
            """ D.viewitems() -> a set-like object providing a view on D's items """
            pass
    
        def viewkeys(self): # real signature unknown; restored from __doc__
            """ D.viewkeys() -> a set-like object providing a view on D's keys """
            pass
    
        def viewvalues(self): # real signature unknown; restored from __doc__
            """ D.viewvalues() -> an object providing a view on D's values """
            pass
    
        def __cmp__(self, y): # real signature unknown; restored from __doc__
            """ x.__cmp__(y) <==> cmp(x,y) """
            pass
    
        def __contains__(self, k): # real signature unknown; restored from __doc__
            """ D.__contains__(k) -> True if D has a key k, else False """
            return False
    
        def __delitem__(self, y): # real signature unknown; restored from __doc__
            """ x.__delitem__(y) <==> del x[y] """
            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 __getitem__(self, y): # real signature unknown; restored from __doc__
            """ x.__getitem__(y) <==> x[y] """
            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 __init__(self, seq=None, **kwargs): # known special case of dict.__init__
            """
            dict() -> new empty dictionary
            dict(mapping) -> new dictionary initialized from a mapping object's
                (key, value) pairs
            dict(iterable) -> new dictionary initialized as if via:
                d = {}
                for k, v in iterable:
                    d[k] = v
            dict(**kwargs) -> new dictionary initialized with the name=value pairs
                in the keyword argument list.  For example:  dict(one=1, two=2)
            # (copied from class doc)
            """
            pass
    
        def __iter__(self): # real signature unknown; restored from __doc__
            """ x.__iter__() <==> iter(x) """
            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 __repr__(self): # real signature unknown; restored from __doc__
            """ x.__repr__() <==> repr(x) """
            pass
    
        def __setitem__(self, i, y): # real signature unknown; restored from __doc__
            """ x.__setitem__(i, y) <==> x[i]=y """
            pass
    
        def __sizeof__(self): # real signature unknown; restored from __doc__
            """ D.__sizeof__() -> size of D in memory, in bytes """
            pass
    
        __hash__ = None
    dict

     

    • 其他

    一、for循环

    用户按照顺序循环可迭代对象中的内容

    1 num = ["404","505","606"]
    2 for item in num:
    3     print(item)

     

     

    二、enumerate

    为可迭代的对象添加序号,自动生成一列,默认从0开始,自增一。

    num = ["404","505","606"]
    for v in enumerate(num):
        print(v)
    #打印结果:
    (0, '404')
    (1, '505')
    (2, '606')

    示例:

    注:字符串转数字时:int(字符串)

    li = ["电脑","鼠标垫","U盘","游艇"]
    for key,item in enumerate(li,1):
        print(key,item)
    inp = input("请选择商品:")
    inp_num = int(inp)
    print(li[inp_num-1])

     通过输入商品取出索引:

    li = ["电脑","鼠标垫","U盘","游艇"]
    print(li)
    inp = input("请输入商品:")
    ret = li.index(inp)
    print(ret)
    #打印结果:
    ['电脑', '鼠标垫', 'U盘', '游艇']
    请输入商品:电脑
    0

    三、range和xrange

    Python2.7

    range:是用来获取指定范围内的数(在内存中创建出来数,占内存)

    xrange:只有通过for循环进行迭代的时候才创建(在内存中不创建)

    Python3

    只有range,等同于Python里面的xrange,通过for循环进行迭代时创建。

    指定范围,生成指定的数字

    1 print range(1, 10)
    2 # 结果:[1, 2, 3, 4, 5, 6, 7, 8, 9]
    3  
    4 print range(1, 10, 2)
    5 # 结果:[1, 3, 5, 7, 9]
    6  
    7 print range(30, 0, -2)
    8 # 结果:[30, 28, 26, 24, 22, 20, 18, 16, 14, 12, 10, 8, 6, 4, 2]  

    只取索引:

    li = ["电脑","鼠标垫","U盘","游艇"]
    len_li = len(li)
    for i in range(len_li):
        print(i)
    #打印结果:
    0
    1
    2
    3
    
    ##########
    li = ["电脑","鼠标垫","U盘","游艇"]
    len_li = len(li)
    for i in range(len_li):
        print(i,li[i])
    #打印结果:
    0 电脑
    1 鼠标垫
    2 U盘
    3 游艇

    练习题

    一、元素分类

    有如下值集合 [11,22,33,44,55,66,77,88,99,90...],将所有大于 66 的值保存至字典的第一个key中,将小于 66 的值保存至第二个key的值中。
    即: {'k1': 大于66的所有值, 'k2': 小于66的所有值}
    li = [11,22,33,44,55,66,77,88,99,90]
    #创建一个空字典
    dic = {
        "k1":[],
        "k2":[]
    }
    #循环li列表
    for i in li:
        if i <= 66: #筛选出<=66的元素
            dic["k1"].append(i) #追加到k1对应的列表里面
        else: #>66的元素
            dic["k2"].append(i) #追加到k2对应的列表里面
    print(dic) #打印出创建的字典
    #打印结果:{'k2': [77, 88, 99, 90], 'k1': [11, 22, 33, 44, 55, 66]}
    View Code

    二、查找

    查找列表中元素,移除每个元素的空格,并查找以 a或A开头 并且以 c 结尾的所有元素。
    li = ["alec", " aric", "Alex", "Tony", "rain"]
    tu = ("alec", " aric", "Alex", "Tony", "rain")
    dic = {'k1': "alex", 'k2': ' aric', "k3": "Alex", "k4": "Tony"}
    for i in li:
        #i 表示每一个元素
        new_i = i.strip()
        #if判断的顺序是从前到后。or,自己成功就行了。and,要继续往后找。
        if (new_i.startswith("a") or new_i.startswith("A")) and new_i.endswith("c"):
            print(new_i)
    #打印结果:aric
    View Code

    三、输出商品列表,用户输入序号,显示用户选中的商品

    li = ["手机", "电脑", '鼠标垫', '游艇']
    for i, j in enumerate(li):
        print(i+1, j)
    num = input('num:')
    # 索引
    num = int(num)
    len_li = len(li)
    if num > 0 and num <= len_li:
        goods = li[num - 1]
        print(goods)
    else:
        print("商品不存在")
    #打印结果:
    1 手机
    2 电脑
    3 鼠标垫
    4 游艇
    num:1
    手机
    
    #打印结果:
    1 手机
    2 电脑
    3 鼠标垫
    4 游艇
    num:5
    商品不存在
    View Code

    四、购物车

    功能要求:

    要求用户输入总资产,例如:2000
    显示商品列表,让用户根据序号选择商品,加入购物车
    购买,如果商品总额大于总资产,提示账户余额不足,否则,购买成功。
    附加:可充值、某商品移除购物车
    goods = [
    {"name": "电脑", "price": 1999},
    {"name": "鼠标", "price": 10},
    {"name": "游艇", "price": 20},
    {"name": "美女", "price": 998},
    ]

    #总资产
    asset_all = 0
    i1 = input("请输入总资产:")
    asset_all = int(i1)
    for i in goods:
        print(i["name"],i["price"])
    car_dict = {}
    while True:
        i2 = input("请选择商品(Y/y结算):")
        if i2.lower() == "y":
            break
        #循环所有的商品,查找需要的商品
        for item in goods:
            if item["name"] == i2:
                name = item["name"]
                if name in car_dict.keys():#判断购物车是否有该商品,有:num + 1
                    car_dict[name]["num"] = car_dict[name]["num"] +1
                else:
                    car_dict[name] = {"num":1,"single_price":item["price"]}
    print(car_dict)
    #循环购买后的购物车
    all_price = 0
    for k,v in car_dict.items():
        n = v["single_price"]
        m = v["num"]
        all_sum = m * n
        all_price = all_price +all_sum
    if all_price > asset_all:
        print("余额不足")
    else:
        print("购买成功")
    View Code

    五、用户交互,显示省市县三级联动的选择

    dic = {
    "河北":{
    "石家庄": ["鹿泉", "藁城", "元氏"],
    "邯郸": ["永年", "涉县", "磁县"],
    },
    "河南":{
    "郑州":["不知道","少林寺","嵩山"],
    "开封":["包拯","展昭","威士忌"],
    },
    "山西":{
    "太原":["xxx","哦哦哦","小店"],
    "运城":["更不知道了","999","哈尔滨啤酒"],
    }
    }

    for x in dic:
        print(x)
    i1 = input("请输入省份:")
    a = dic[i1]
    #循环输出所有的城市
    for j in a:
        print(j)
    i2 = input("请输入城市:")
    b = dic[i1][i2]
    for z in b:
        print(z)
    #打印结果:
    山西
    河南
    河北
    请输入省份:河北
    邯郸
    石家庄
    请输入城市:石家庄
    鹿泉
    藁城
    元氏
    View Code


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  • 原文地址:https://www.cnblogs.com/0820-zq/p/5452888.html
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