第三篇：python基础之数据类型与变量
阅读目录
- 一.变量
- 二.数据类型
- 2.1 什么是数据类型及数据类型分类
- 2.2 标准数据类型：
- 2.2.1 数字
- 2.2.1.1 整型:
- 2.2.1.2 长整型long：
- 2.2.1.3 布尔bool:
- 2.2.1.4 浮点数float:
- 2.2.1.5 复数complex:
- 2.2.1.6 数字相关内建函数
- 2.2.2 字符串
- 2.2.2.1 字符串创建
- 2.2.2.2 字符串常用操作
- 2.2.2.3 字符工厂函数str()
- 2.2.3 列表
- 2.2.3.1 列表创建
- 2.2.3.2 列表常用操作
- 2.2.3.3 列表工厂函数list()
- 2.2.4 元组
- 2.2.4.1 元组创建
- 2.2.4.2 元组常用操作
- 2.2.4.3 元组工厂函数tuple()
- 2.2.5 字典
- 2.2.5.1 字典创建
- 2.2.5.2 字典常用操作
- 2.2.5.3 字典工厂函数dict()
- 2.2.6 集合
- 2.2.6.1 集合创建
- 2.2.6.2 集合常用操作：关系运算
- 2.2.6.3 集合工厂函数set()
- 2.2.7 bytes类型
- 2.2.8 数据类型转换内置函数汇总
- 三.运算符
- 四.标准数据类型特性总结
一.变量
1 什么是变量之声明变量
#变量名=变量值
age=18
gender1='male'
gender2='female'
2 为什么要有变量 变量作用：“变”=>变化，“量”=>计量/保存状态
程序的运行本质是一系列状态的变化，变量的目的就是用来保存状态，变量值的变化就构成了程序运行的不同结果。
例如：CS枪战，一个人的生命可以表示为life＝active表示存活，当满足某种条件后修改变量life＝inactive表示死亡。
3 变量值之类型与对象
程序中需要处理的状态很多，于是有了不同类型的变量值，x='egon',变量值'egon'存放与内存中，绑定一个名字x，变量值即我们要存储的数据。 在python中所有数据都是围绕对象这个概念来构建的，对象包含一些基本的数据类型：数字，字符串，列表，元组，字典等
程序中存储的所有数据都是对象，
一个对象（如a=1）有：
一个身份（id）
一个类型(type)
一个值(通过变量名a来查看)
1 对象的类型也称为对象的类别，python为每个类型都定制了属于该类型特有的方法，极大地方便了开发者对数据的处理
2 创建某个特定类型的对象也称为创建了该类型的一个实例，工厂函数的概念来源于此
4 可变对象与不可变对象
实例被创建后，身份和类型是不可变的，
如果值是不可以被修改的，则是不可变对象
如果值是可以被修改的，则是可变对象 5 容器对象
某个对象包含对其他对象的引用，则称为容器或集合 6 对象的属性和方法
属性就是对象的值，方法就是调用时将在对象本身上执行某些操作的函数，使用.运算符可以访问对象的属性和方法，如
a=3+4j
a.real b=[1,2,3]
b.append(4) 7 身份比较，类型比较，值比较
x=1
y=1
x is y #x与y是同一个对象，is比较的是id，即身份
type(x) is type(y) #对象的类型本身也是一个对象，所以可以用is比较两个对象的类型的身份
x == y #==比较的是两个对象的值是否相等 7 变量的命名规范
- 变量命名规则遵循标识符命名规则，详见第二篇
8 变量的赋值操作
- 与c语言的区别在于变量赋值操作无返回值
- 链式赋值：y＝x＝a＝1
- 多元赋值：x,y=1,2 x,y=y,x
- 增量赋值：x+=1
二.数据类型
2.1 什么是数据类型及数据类型分类
程序的本质就是驱使计算机去处理各种状态的变化，这些状态分为很多种 例如英雄联盟游戏，一个人物角色有名字，钱，等级，装备等特性，大家第一时间会想到这么表示
名字：德玛西亚－－－－－－－－－－－－>字符串
钱：10000 －－－－－－－－－－－－>数字
等级：15 －－－－－－－－－－－－>数字
装备：鞋子，日炎斗篷，兰顿之兆－－－－>列表
(记录这些人物特性的是变量，这些特性的真实存在则是变量的值，存不同的特性需要用不同类型的值) python中的数据类型
python使用对象模型来存储数据，每一个数据类型都有一个内置的类，每新建一个数据，实际就是在初始化生成一个对象，即所有数据都是对象
对象三个特性
- 身份：内存地址，可以用id()获取
- 类型：决定了该对象可以保存什么类型值，可执行何种操作，需遵循什么规则，可用type()获取
- 值：对象保存的真实数据
注：我们在定义数据类型，只需这样：x＝1，内部生成1这一内存对象会自动触发，我们无需关心 这里的字符串、数字、列表等都是数据类型（用来描述某种状态或者特性）除此之外还有很多其他数据，处理不同的数据就需要定义不同的数据类型
| 标准类型 | 其他类型 |
| 数字 | 类型type |
| 字符串 | Null |
| 列表 | 文件 |
| 元组 | 集合 |
| 字典 | 函数／方法 |
| 类 | |
| 模块 |
2.2 标准数据类型：
2.2.1 数字
定义：a＝1
特性：
1.只能存放一个值
2.一经定义，不可更改
3.直接访问
分类：整型，长整型，布尔，浮点，复数
2.2.1.1 整型:
Python的整型相当于C中的long型,Python中的整数可以用十进制,八进制,十六进制表示。
>>> 10
10 --------->默认十进制
>>> oct(10)
'' --------->八进制表示整数时，数值前面要加上一个前缀“0”
>>> hex(10)
'0xa' --------->十六进制表示整数时，数字前面要加上前缀0X或0x
python2.*与python3.*关于整型的区别
python2.*
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-9223372036854775808～9223372036854775807
python3.*整形长度无限制
整型工厂函数int()
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)
"""
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()
"""
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)
# (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
python2.7
class int(object):
"""
int(x=0) -> integer
int(x, base=10) -> integer Convert a number or string to an integer, or return 0 if no arguments
are given. If x is a number, return x.__int__(). For floating point
numbers, this truncates towards zero. If x is not a number or if base is given, then x must be a string,
bytes, or bytearray instance 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): # real signature unknown; restored from __doc__
""" 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 @classmethod # known case
def from_bytes(cls, bytes, byteorder, *args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__
"""
int.from_bytes(bytes, byteorder, *, signed=False) -> int Return the integer represented by the given array of bytes. The bytes argument must be a bytes-like object (e.g. bytes or bytearray). The byteorder argument determines the byte order used to represent the
integer. If byteorder is 'big', the most significant byte is at the
beginning of the byte array. If byteorder is 'little', the most
significant byte is at the end of the byte array. To request the native
byte order of the host system, use `sys.byteorder' as the byte order value. The signed keyword-only argument indicates whether two's complement is
used to represent the integer.
"""
pass def to_bytes(self, length, byteorder, *args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__
"""
int.to_bytes(length, byteorder, *, signed=False) -> bytes Return an array of bytes representing an integer. The integer is represented using length bytes. An OverflowError is
raised if the integer is not representable with the given number of
bytes. The byteorder argument determines the byte order used to represent the
integer. If byteorder is 'big', the most significant byte is at the
beginning of the byte array. If byteorder is 'little', the most
significant byte is at the end of the byte array. To request the native
byte order of the host system, use `sys.byteorder' as the byte order value. The signed keyword-only argument determines whether two's complement is
used to represent the integer. If signed is False and a negative integer
is given, an OverflowError is raised.
"""
pass def __abs__(self, *args, **kwargs): # real signature unknown
""" abs(self) """
pass def __add__(self, *args, **kwargs): # real signature unknown
""" Return self+value. """
pass def __and__(self, *args, **kwargs): # real signature unknown
""" Return self&value. """
pass def __bool__(self, *args, **kwargs): # real signature unknown
""" self != 0 """
pass def __ceil__(self, *args, **kwargs): # real signature unknown
"""
整数返回自己
如果是小数
math.ceil(3.1)返回4
"""
""" Ceiling of an Integral returns itself. """
pass def __divmod__(self, *args, **kwargs): # real signature unknown
""" 相除，得到商和余数组成的元组 """
""" Return divmod(self, value). """
pass def __eq__(self, *args, **kwargs): # real signature unknown
""" Return self==value. """
pass def __float__(self, *args, **kwargs): # real signature unknown
""" float(self) """
pass def __floordiv__(self, *args, **kwargs): # real signature unknown
""" Return self//value. """
pass def __floor__(self, *args, **kwargs): # real signature unknown
""" Flooring an Integral returns itself. """
pass def __format__(self, *args, **kwargs): # real signature unknown
pass def __getattribute__(self, *args, **kwargs): # real signature unknown
""" Return getattr(self, name). """
pass def __getnewargs__(self, *args, **kwargs): # real signature unknown
pass def __ge__(self, *args, **kwargs): # real signature unknown
""" Return self>=value. """
pass def __gt__(self, *args, **kwargs): # real signature unknown
""" Return self>value. """
pass def __hash__(self, *args, **kwargs): # real signature unknown
""" Return hash(self). """
pass def __index__(self, *args, **kwargs): # real signature unknown
""" 用于切片，数字无意义 """
""" Return self converted to an integer, if self is suitable for use as an index into a list. """
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) -> integer
int(x, base=10) -> integer Convert a number or string to an integer, or return 0 if no arguments
are given. If x is a number, return x.__int__(). For floating point
numbers, this truncates towards zero. If x is not a number or if base is given, then x must be a string,
bytes, or bytearray instance 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, *args, **kwargs): # real signature unknown """ int(self) """
pass def __invert__(self, *args, **kwargs): # real signature unknown
""" ~self """
pass def __le__(self, *args, **kwargs): # real signature unknown
""" Return self<=value. """
pass def __lshift__(self, *args, **kwargs): # real signature unknown
""" Return self<<value. """
pass def __lt__(self, *args, **kwargs): # real signature unknown
""" Return self<value. """
pass def __mod__(self, *args, **kwargs): # real signature unknown
""" Return self%value. """
pass def __mul__(self, *args, **kwargs): # real signature unknown
""" Return self*value. """
pass def __neg__(self, *args, **kwargs): # real signature unknown
""" -self """
pass @staticmethod # known case of __new__
def __new__(*args, **kwargs): # real signature unknown
""" Create and return a new object. See help(type) for accurate signature. """
pass def __ne__(self, *args, **kwargs): # real signature unknown
""" Return self!=value. """
pass def __or__(self, *args, **kwargs): # real signature unknown
""" Return self|value. """
pass def __pos__(self, *args, **kwargs): # real signature unknown
""" +self """
pass def __pow__(self, *args, **kwargs): # real signature unknown
""" Return pow(self, value, mod). """
pass def __radd__(self, *args, **kwargs): # real signature unknown
""" Return value+self. """
pass def __rand__(self, *args, **kwargs): # real signature unknown
""" Return value&self. """
pass def __rdivmod__(self, *args, **kwargs): # real signature unknown
""" Return divmod(value, self). """
pass def __repr__(self, *args, **kwargs): # real signature unknown
""" Return repr(self). """
pass def __rfloordiv__(self, *args, **kwargs): # real signature unknown
""" Return value//self. """
pass def __rlshift__(self, *args, **kwargs): # real signature unknown
""" Return value<<self. """
pass def __rmod__(self, *args, **kwargs): # real signature unknown
""" Return value%self. """
pass def __rmul__(self, *args, **kwargs): # real signature unknown
""" Return value*self. """
pass def __ror__(self, *args, **kwargs): # real signature unknown
""" Return value|self. """
pass def __round__(self, *args, **kwargs): # real signature unknown
"""
Rounding an Integral returns itself.
Rounding with an ndigits argument also returns an integer.
"""
pass def __rpow__(self, *args, **kwargs): # real signature unknown
""" Return pow(value, self, mod). """
pass def __rrshift__(self, *args, **kwargs): # real signature unknown
""" Return value>>self. """
pass def __rshift__(self, *args, **kwargs): # real signature unknown
""" Return self>>value. """
pass def __rsub__(self, *args, **kwargs): # real signature unknown
""" Return value-self. """
pass def __rtruediv__(self, *args, **kwargs): # real signature unknown
""" Return value/self. """
pass def __rxor__(self, *args, **kwargs): # real signature unknown
""" Return value^self. """
pass def __sizeof__(self, *args, **kwargs): # real signature unknown
""" Returns size in memory, in bytes """
pass def __str__(self, *args, **kwargs): # real signature unknown
""" Return str(self). """
pass def __sub__(self, *args, **kwargs): # real signature unknown
""" Return self-value. """
pass def __truediv__(self, *args, **kwargs): # real signature unknown
""" Return self/value. """
pass def __trunc__(self, *args, **kwargs): # real signature unknown
""" Truncating an Integral returns itself. """
pass def __xor__(self, *args, **kwargs): # real signature unknown
""" Return self^value. """
pass denominator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the denominator of a rational number in lowest terms""" imag = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the imaginary part of a complex number""" numerator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the numerator of a rational number in lowest terms""" real = property(lambda self: object(), lambda self, v: None, lambda self: None) # default
"""the real part of a complex number"""
python3.5
2.2.1.2 长整型long：
python2.*：
跟C语言不同，Python的长整型没有指定位宽，也就是说Python没有限制长整型数值的大小，
但是实际上由于机器内存有限，所以我们使用的长整型数值不可能无限大。
在使用过程中，我们如何区分长整型和整型数值呢？
通常的做法是在数字尾部加上一个大写字母L或小写字母l以表示该整数是长整型的，例如：
a = 9223372036854775808L
注意，自从Python2起，如果发生溢出，Python会自动将整型数据转换为长整型，
所以如今在长整型数据后面不加字母L也不会导致严重后果了。 python3.*
长整型，整型统一归为整型
python2.7
>>> a=9223372036854775807
>>> a
9223372036854775807
>>> a+=1
>>> a
9223372036854775808L python3.5
>>> a=9223372036854775807
>>> a
9223372036854775807
>>> a+=1
>>> a
9223372036854775808
查看
2.2.1.3 布尔bool:
True 和False
1和0
2.2.1.4 浮点数float:
Python的浮点数就是数学中的小数，类似C语言中的double。
在运算中，整数与浮点数运算的结果是浮点数
浮点数也就是小数，之所以称为浮点数，是因为按照科学记数法表示时，
一个浮点数的小数点位置是可变的，比如，1.23*109和12.3*108是相等的。
浮点数可以用数学写法，如1.23，3.14，-9.01，等等。但是对于很大或很小的浮点数，
就必须用科学计数法表示，把10用e替代，1.23*109就是1.23e9，或者12.3e8，0.000012
可以写成1.2e-5，等等。
整数和浮点数在计算机内部存储的方式是不同的，整数运算永远是精确的而浮点数运算则可能会有
四舍五入的误差。
2.2.1.5 复数complex:
复数由实数部分和虚数部分组成，一般形式为x＋yj，其中的x是复数的实数部分，y是复数的虚数部分，这里的x和y都是实数。
注意，虚数部分的字母j大小写都可以，
>>> 1.3 + 2.5j == 1.3 + 2.5J
True
2.2.1.6 数字相关内建函数
2.2.2 字符串
定义：它是一个有序的字符的集合，用于存储和表示基本的文本信息，‘’或“”或‘’‘ ’‘’中间包含的内容称之为字符串
特性：
1.只能存放一个值
2.不可变
3.按照从左到右的顺序定义字符集合，下标从0开始顺序访问，有序
补充：
1.字符串的单引号和双引号都无法取消特殊字符的含义，如果想让引号内所有字符均取消特殊意义，在引号前面加r，如name＝r'l\thf'
2.unicode字符串与r连用必需在r前面，如name＝ur'l\thf'
2.2.2.1 字符串创建
‘hello world’
2.2.2.2 字符串常用操作
移除空白
分割
长度
索引
切片
2.2.2.3 字符工厂函数str()
class str(object):
"""
str(object='') -> str
str(bytes_or_buffer[, encoding[, errors]]) -> str Create a new string object from the given object. If encoding or
errors is specified, then the object must expose a data buffer
that will be decoded using the given encoding and error handler.
Otherwise, returns the result of object.__str__() (if defined)
or repr(object).
encoding defaults to sys.getdefaultencoding().
errors defaults to 'strict'.
"""
def capitalize(self): # real signature unknown; restored from __doc__
"""
首字母变大写
S.capitalize() -> str Return a capitalized version of S, i.e. make the first character
have upper case and the rest lower case.
"""
return "" def casefold(self): # real signature unknown; restored from __doc__
"""
S.casefold() -> str Return a version of S suitable for caseless comparisons.
"""
return "" def center(self, width, fillchar=None): # real signature unknown; restored from __doc__
"""
原来字符居中，不够用空格补全
S.center(width[, fillchar]) -> str Return S centered in a string of length width. Padding is
done using the specified fill character (default is a space)
"""
return "" def count(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
"""
从一个范围内的统计某str出现次数
S.count(sub[, start[, end]]) -> int Return the number of non-overlapping occurrences of substring sub in
string S[start:end]. Optional arguments start and end are
interpreted as in slice notation.
"""
return 0 def encode(self, encoding='utf-8', errors='strict'): # real signature unknown; restored from __doc__
"""
encode(encoding='utf-8',errors='strict')
以encoding指定编码格式编码，如果出错默认报一个ValueError，除非errors指定的是
ignore或replace S.encode(encoding='utf-8', errors='strict') -> bytes Encode S using the codec registered for encoding. Default encoding
is 'utf-8'. errors may be given to set a different error
handling scheme. Default is 'strict' meaning that encoding errors raise
a UnicodeEncodeError. Other possible values are 'ignore', 'replace' and
'xmlcharrefreplace' as well as any other name registered with
codecs.register_error that can handle UnicodeEncodeErrors.
"""
return b"" def endswith(self, suffix, start=None, end=None): # real signature unknown; restored from __doc__
"""
S.endswith(suffix[, start[, end]]) -> bool Return True if S ends with the specified suffix, False otherwise.
With optional start, test S beginning at that position.
With optional end, stop comparing S at that position.
suffix can also be a tuple of strings to try.
"""
return False def expandtabs(self, tabsize=8): # real signature unknown; restored from __doc__
"""
将字符串中包含的\t转换成tabsize个空格
S.expandtabs(tabsize=8) -> str Return a copy of S where all tab characters are expanded using spaces.
If tabsize is not given, a tab size of 8 characters is assumed.
"""
return "" def find(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
"""
S.find(sub[, start[, end]]) -> int Return the lowest index in S where substring sub is found,
such that sub is contained within S[start:end]. Optional
arguments start and end are interpreted as in slice notation. Return -1 on failure.
"""
return 0 def format(self, *args, **kwargs): # known special case of str.format
"""
格式化输出
三种形式：
形式一.
>>> print('{0}{1}{0}'.format('a','b'))
aba 形式二：（必须一一对应）
>>> print('{}{}{}'.format('a','b'))
Traceback (most recent call last):
File "<input>", line 1, in <module>
IndexError: tuple index out of range
>>> print('{}{}'.format('a','b'))
ab 形式三：
>>> print('{name} {age}'.format(age=12,name='lhf'))
lhf 12 S.format(*args, **kwargs) -> str Return a formatted version of S, using substitutions from args and kwargs.
The substitutions are identified by braces ('{' and '}').
"""
pass def format_map(self, mapping): # real signature unknown; restored from __doc__
"""
与format区别
'{name}'.format(**dict(name='alex'))
'{name}'.format_map(dict(name='alex')) S.format_map(mapping) -> str Return a formatted version of S, using substitutions from mapping.
The substitutions are identified by braces ('{' and '}').
"""
return "" def index(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
"""
S.index(sub[, start[, end]]) -> int Like S.find() but raise ValueError when the substring is not found.
"""
return 0 def isalnum(self): # real signature unknown; restored from __doc__
"""
至少一个字符，且都是字母或数字才返回True S.isalnum() -> bool Return True if all characters in S are alphanumeric
and there is at least one character in S, False otherwise.
"""
return False def isalpha(self): # real signature unknown; restored from __doc__
"""
至少一个字符，且都是字母才返回True
S.isalpha() -> bool Return True if all characters in S are alphabetic
and there is at least one character in S, False otherwise.
"""
return False def isdecimal(self): # real signature unknown; restored from __doc__
"""
S.isdecimal() -> bool Return True if there are only decimal characters in S,
False otherwise.
"""
return False def isdigit(self): # real signature unknown; restored from __doc__
"""
S.isdigit() -> bool Return True if all characters in S are digits
and there is at least one character in S, False otherwise.
"""
return False def isidentifier(self): # real signature unknown; restored from __doc__
"""
字符串为关键字返回True S.isidentifier() -> bool Return True if S is a valid identifier according
to the language definition. Use keyword.iskeyword() to test for reserved identifiers
such as "def" and "class".
"""
return False def islower(self): # real signature unknown; restored from __doc__
"""
至少一个字符，且都是小写字母才返回True
S.islower() -> bool Return True if all cased characters in S are lowercase and there is
at least one cased character in S, False otherwise.
"""
return False def isnumeric(self): # real signature unknown; restored from __doc__
"""
S.isnumeric() -> bool Return True if there are only numeric characters in S,
False otherwise.
"""
return False def isprintable(self): # real signature unknown; restored from __doc__
"""
S.isprintable() -> bool Return True if all characters in S are considered
printable in repr() or S is empty, False otherwise.
"""
return False def isspace(self): # real signature unknown; restored from __doc__
"""
至少一个字符，且都是空格才返回True
S.isspace() -> bool Return True if all characters in S are whitespace
and there is at least one character in S, False otherwise.
"""
return False def istitle(self): # real signature unknown; restored from __doc__
"""
>>> a='Hello'
>>> a.istitle()
True
>>> a='HellP'
>>> a.istitle()
False S.istitle() -> bool Return True if S is a titlecased string and there is at least one
character in S, i.e. upper- and titlecase characters may only
follow uncased characters and lowercase characters only cased ones.
Return False otherwise.
"""
return False def isupper(self): # real signature unknown; restored from __doc__
"""
S.isupper() -> bool Return True if all cased characters in S are uppercase and there is
at least one cased character in S, False otherwise.
"""
return False def join(self, iterable): # real signature unknown; restored from __doc__
"""
#对序列进行操作（分别使用' '与':'作为分隔符）
>>> seq1 = ['hello','good','boy','doiido']
>>> print ' '.join(seq1)
hello good boy doiido
>>> print ':'.join(seq1)
hello:good:boy:doiido #对字符串进行操作 >>> seq2 = "hello good boy doiido"
>>> print ':'.join(seq2)
h:e:l:l:o: :g:o:o:d: :b:o:y: :d:o:i:i:d:o #对元组进行操作 >>> seq3 = ('hello','good','boy','doiido')
>>> print ':'.join(seq3)
hello:good:boy:doiido #对字典进行操作 >>> seq4 = {'hello':1,'good':2,'boy':3,'doiido':4}
>>> print ':'.join(seq4)
boy:good:doiido:hello #合并目录 >>> import os
>>> os.path.join('/hello/','good/boy/','doiido')
'/hello/good/boy/doiido' S.join(iterable) -> str Return a string which is the concatenation of the strings in the
iterable. The separator between elements is S.
"""
return "" def ljust(self, width, fillchar=None): # real signature unknown; restored from __doc__
"""
S.ljust(width[, fillchar]) -> str Return S left-justified in a Unicode string of length width. Padding is
done using the specified fill character (default is a space).
"""
return "" def lower(self): # real signature unknown; restored from __doc__
"""
S.lower() -> str Return a copy of the string S converted to lowercase.
"""
return "" def lstrip(self, chars=None): # real signature unknown; restored from __doc__
"""
S.lstrip([chars]) -> str Return a copy of the string S with leading whitespace removed.
If chars is given and not None, remove characters in chars instead.
"""
return "" def maketrans(self, *args, **kwargs): # real signature unknown
"""
Return a translation table usable for str.translate(). If there is only one argument, it must be a dictionary mapping Unicode
ordinals (integers) or characters to Unicode ordinals, strings or None.
Character keys will be then converted to ordinals.
If there are two arguments, they must be strings of equal length, and
in the resulting dictionary, each character in x will be mapped to the
character at the same position in y. If there is a third argument, it
must be a string, whose characters will be mapped to None in the result.
"""
pass def partition(self, sep): # real signature unknown; restored from __doc__
"""
以sep为分割，将S分成head,sep,tail三部分 S.partition(sep) -> (head, sep, tail) Search for the separator sep in S, and return the part before it,
the separator itself, and the part after it. If the separator is not
found, return S and two empty strings.
"""
pass def replace(self, old, new, count=None): # real signature unknown; restored from __doc__
"""
S.replace(old, new[, count]) -> str Return a copy of S with all occurrences of substring
old replaced by new. If the optional argument count is
given, only the first count occurrences are replaced.
"""
return "" def rfind(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
"""
S.rfind(sub[, start[, end]]) -> int Return the highest index in S where substring sub is found,
such that sub is contained within S[start:end]. Optional
arguments start and end are interpreted as in slice notation. Return -1 on failure.
"""
return 0 def rindex(self, sub, start=None, end=None): # real signature unknown; restored from __doc__
"""
S.rindex(sub[, start[, end]]) -> int Like S.rfind() but raise ValueError when the substring is not found.
"""
return 0 def rjust(self, width, fillchar=None): # real signature unknown; restored from __doc__
"""
S.rjust(width[, fillchar]) -> str Return S right-justified in a string of length width. Padding is
done using the specified fill character (default is a space).
"""
return "" def rpartition(self, sep): # real signature unknown; restored from __doc__
"""
S.rpartition(sep) -> (head, sep, tail) Search for the separator sep in S, starting at the end of S, and return
the part before it, the separator itself, and the part after it. If the
separator is not found, return two empty strings and S.
"""
pass def rsplit(self, sep=None, maxsplit=-1): # real signature unknown; restored from __doc__
"""
S.rsplit(sep=None, maxsplit=-1) -> list of strings Return a list of the words in S, using sep as the
delimiter string, starting at the end of the string and
working to the front. If maxsplit is given, at most maxsplit
splits are done. If sep is not specified, any whitespace string
is a separator.
"""
return [] def rstrip(self, chars=None): # real signature unknown; restored from __doc__
"""
S.rstrip([chars]) -> str Return a copy of the string S with trailing whitespace removed.
If chars is given and not None, remove characters in chars instead.
"""
return "" def split(self, sep=None, maxsplit=-1): # real signature unknown; restored from __doc__
"""
以sep为分割，将S切分成列表，与partition的区别在于切分结果不包含sep，
如果一个字符串中包含多个sep那么maxsplit为最多切分成几部分
>>> a='a,b c\nd\te'
>>> a.split()
['a,b', 'c', 'd', 'e']
S.split(sep=None, maxsplit=-1) -> list of strings Return a list of the words in S, using sep as the
delimiter string. If maxsplit is given, at most maxsplit
splits are done. If sep is not specified or is None, any
whitespace string is a separator and empty strings are
removed from the result.
"""
return [] def splitlines(self, keepends=None): # real signature unknown; restored from __doc__
"""
Python splitlines() 按照行('\r', '\r\n', \n')分隔，
返回一个包含各行作为元素的列表，如果参数 keepends 为 False，不包含换行符，如 果为 True，则保留换行符。
>>> x
'adsfasdf\nsadf\nasdf\nadf'
>>> x.splitlines()
['adsfasdf', 'sadf', 'asdf', 'adf']
>>> x.splitlines(True)
['adsfasdf\n', 'sadf\n', 'asdf\n', 'adf'] S.splitlines([keepends]) -> list of strings Return a list of the lines in S, breaking at line boundaries.
Line breaks are not included in the resulting list unless keepends
is given and true.
"""
return [] def startswith(self, prefix, start=None, end=None): # real signature unknown; restored from __doc__
"""
S.startswith(prefix[, start[, end]]) -> bool Return True if S starts with the specified prefix, False otherwise.
With optional start, test S beginning at that position.
With optional end, stop comparing S at that position.
prefix can also be a tuple of strings to try.
"""
return False def strip(self, chars=None): # real signature unknown; restored from __doc__
"""
S.strip([chars]) -> str Return a copy of the string S with leading and trailing
whitespace removed.
If chars is given and not None, remove characters in chars instead.
"""
return "" def swapcase(self): # real signature unknown; restored from __doc__
"""
大小写反转
S.swapcase() -> str Return a copy of S with uppercase characters converted to lowercase
and vice versa.
"""
return "" def title(self): # real signature unknown; restored from __doc__
"""
S.title() -> str Return a titlecased version of S, i.e. words start with title case
characters, all remaining cased characters have lower case.
"""
return "" def translate(self, table): # real signature unknown; restored from __doc__
"""
table=str.maketrans('alex','big SB') a='hello abc'
print(a.translate(table)) S.translate(table) -> str Return a copy of the string S in which each character has been mapped
through the given translation table. The table must implement
lookup/indexing via __getitem__, for instance a dictionary or list,
mapping Unicode ordinals to Unicode ordinals, strings, or None. If
this operation raises LookupError, the character is left untouched.
Characters mapped to None are deleted.
"""
return "" def upper(self): # real signature unknown; restored from __doc__
"""
S.upper() -> str Return a copy of S converted to uppercase.
"""
return "" def zfill(self, width): # real signature unknown; restored from __doc__
"""
原来字符右对齐，不够用0补齐 S.zfill(width) -> str Pad a numeric string S with zeros on the left, to fill a field
of the specified width. The string S is never truncated.
"""
return "" def __add__(self, *args, **kwargs): # real signature unknown
""" Return self+value. """
pass def __contains__(self, *args, **kwargs): # real signature unknown
""" Return key in self. """
pass def __eq__(self, *args, **kwargs): # real signature unknown
""" Return self==value. """
pass def __format__(self, format_spec): # real signature unknown; restored from __doc__
"""
S.__format__(format_spec) -> str Return a formatted version of S as described by format_spec.
"""
return "" def __getattribute__(self, *args, **kwargs): # real signature unknown
""" Return getattr(self, name). """
pass def __getitem__(self, *args, **kwargs): # real signature unknown
""" Return self[key]. """
pass def __getnewargs__(self, *args, **kwargs): # real signature unknown
pass def __ge__(self, *args, **kwargs): # real signature unknown
""" Return self>=value. """
pass def __gt__(self, *args, **kwargs): # real signature unknown
""" Return self>value. """
pass def __hash__(self, *args, **kwargs): # real signature unknown
""" Return hash(self). """
pass def __init__(self, value='', encoding=None, errors='strict'): # known special case of str.__init__
"""
str(object='') -> str
str(bytes_or_buffer[, encoding[, errors]]) -> str Create a new string object from the given object. If encoding or
errors is specified, then the object must expose a data buffer
that will be decoded using the given encoding and error handler.
Otherwise, returns the result of object.__str__() (if defined)
or repr(object).
encoding defaults to sys.getdefaultencoding().
errors defaults to 'strict'.
# (copied from class doc)
"""
pass def __iter__(self, *args, **kwargs): # real signature unknown
""" Implement iter(self). """
pass def __len__(self, *args, **kwargs): # real signature unknown
""" Return len(self). """
pass def __le__(self, *args, **kwargs): # real signature unknown
""" Return self<=value. """
pass def __lt__(self, *args, **kwargs): # real signature unknown
""" Return self<value. """
pass def __mod__(self, *args, **kwargs): # real signature unknown
""" Return self%value. """
pass def __mul__(self, *args, **kwargs): # real signature unknown
""" Return self*value.n """
pass @staticmethod # known case of __new__
def __new__(*args, **kwargs): # real signature unknown
""" Create and return a new object. See help(type) for accurate signature. """
pass def __ne__(self, *args, **kwargs): # real signature unknown
""" Return self!=value. """
pass def __repr__(self, *args, **kwargs): # real signature unknown
""" Return repr(self). """
pass def __rmod__(self, *args, **kwargs): # real signature unknown
""" Return value%self. """
pass def __rmul__(self, *args, **kwargs): # real signature unknown
""" Return self*value. """
pass def __sizeof__(self): # real signature unknown; restored from __doc__
""" S.__sizeof__() -> size of S in memory, in bytes """
pass def __str__(self, *args, **kwargs): # real signature unknown
""" Return str(self). """
pass 字符串工厂函数
字符串工厂函数
num = "" #unicode
num.isdigit() # True
num.isdecimal() # True
num.isnumeric() # True num = "" # 全角
num.isdigit() # True
num.isdecimal() # True
num.isnumeric() # True num = b"" # byte
num.isdigit() # True
num.isdecimal() # AttributeError 'bytes' object has no attribute 'isdecimal'
num.isnumeric() # AttributeError 'bytes' object has no attribute 'isnumeric' num = "IV" # 罗马数字
num.isdigit() # True
num.isdecimal() # False
num.isnumeric() # True num = "四" # 汉字
num.isdigit() # False
num.isdecimal() # False
num.isnumeric() # True ===================
isdigit()
True: Unicode数字，byte数字（单字节），全角数字（双字节），罗马数字
False: 汉字数字
Error: 无 isdecimal()
True: Unicode数字，，全角数字（双字节）
False: 罗马数字，汉字数字
Error: byte数字（单字节） isnumeric()
True: Unicode数字，全角数字（双字节），罗马数字，汉字数字
False: 无
Error: byte数字（单字节） ================
import unicodedata unicodedata.digit("") #
unicodedata.decimal("") #
unicodedata.numeric("") # 2.0 unicodedata.digit("") #
unicodedata.decimal("") #
unicodedata.numeric("") # 2.0 unicodedata.digit(b"") # TypeError: must be str, not bytes
unicodedata.decimal(b"") # TypeError: must be str, not bytes
unicodedata.numeric(b"") # TypeError: must be str, not bytes unicodedata.digit("Ⅷ") # ValueError: not a digit
unicodedata.decimal("Ⅷ") # ValueError: not a decimal
unicodedata.numeric("Ⅷ") # 8.0 unicodedata.digit("四") # ValueError: not a digit
unicodedata.decimal("四") # ValueError: not a decimal
unicodedata.numeric("四") # 4.0 #"〇","零","一","壱","二","弐","三","参","四","五","六","七","八","九","十","廿","卅","卌","百","千","万","万","亿"
python中str函数isdigit、isdecimal、isnumeric的区别
2.2.3 列表
定义：[]内以逗号分隔，按照索引，存放各种数据类型，每个位置代表一个元素
特性：
1.可存放多个值
2.可修改指定索引位置对应的值，可变
3.按照从左到右的顺序定义列表元素，下标从0开始顺序访问，有序
2.2.3.1 列表创建
list_test=[’lhf‘,12,'ok']
或
list_test=list('abc')
或
list_test=list([’lhf‘,12,'ok'])
2.2.3.2 列表常用操作
索引
切片
追加
删除
长度
切片
循环
包含
2.2.3.3 列表工厂函数list()
class list(object):
"""
list() -> new empty list
list(iterable) -> new list initialized from iterable's items
"""
def append(self, p_object): # real signature unknown; restored from __doc__
""" L.append(object) -> None -- append object to end """
pass def clear(self): # real signature unknown; restored from __doc__
""" L.clear() -> None -- remove all items from L """
pass def copy(self): # real signature unknown; restored from __doc__
""" L.copy() -> list -- a shallow copy of L """
return [] def count(self, value): # real signature unknown; restored from __doc__
""" L.count(value) -> integer -- return number of occurrences of value """
return 0 def extend(self, iterable): # real signature unknown; restored from __doc__
""" L.extend(iterable) -> None -- extend list by appending elements from the iterable """
pass def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__
"""
L.index(value, [start, [stop]]) -> integer -- return first index of value.
Raises ValueError if the value is not present.
"""
return 0 def insert(self, index, p_object): # real signature unknown; restored from __doc__
""" L.insert(index, object) -- insert object before index """
pass def pop(self, index=None): # real signature unknown; restored from __doc__
"""
L.pop([index]) -> item -- remove and return item at index (default last).
Raises IndexError if list is empty or index is out of range.
"""
pass def remove(self, value): # real signature unknown; restored from __doc__
"""
L.remove(value) -> None -- remove first occurrence of value.
Raises ValueError if the value is not present.
"""
pass def reverse(self): # real signature unknown; restored from __doc__
""" L.reverse() -- reverse *IN PLACE* """
pass def sort(self, key=None, reverse=False): # real signature unknown; restored from __doc__
""" L.sort(key=None, reverse=False) -> None -- stable sort *IN PLACE* """
pass def __add__(self, *args, **kwargs): # real signature unknown
""" Return self+value. """
pass def __contains__(self, *args, **kwargs): # real signature unknown
""" Return key in self. """
pass def __delitem__(self, *args, **kwargs): # real signature unknown
""" Delete self[key]. """
pass def __eq__(self, *args, **kwargs): # real signature unknown
""" Return self==value. """
pass def __getattribute__(self, *args, **kwargs): # real signature unknown
""" Return getattr(self, name). """
pass def __getitem__(self, y): # real signature unknown; restored from __doc__
""" x.__getitem__(y) <==> x[y] """
pass def __ge__(self, *args, **kwargs): # real signature unknown
""" Return self>=value. """
pass def __gt__(self, *args, **kwargs): # real signature unknown
""" Return self>value. """
pass def __iadd__(self, *args, **kwargs): # real signature unknown
""" Implement self+=value. """
pass def __imul__(self, *args, **kwargs): # real signature unknown
""" Implement self*=value. """
pass def __init__(self, seq=()): # known special case of list.__init__
"""
list() -> new empty list
list(iterable) -> new list initialized from iterable's items
# (copied from class doc)
"""
pass def __iter__(self, *args, **kwargs): # real signature unknown
""" Implement iter(self). """
pass def __len__(self, *args, **kwargs): # real signature unknown
""" Return len(self). """
pass def __le__(self, *args, **kwargs): # real signature unknown
""" Return self<=value. """
pass def __lt__(self, *args, **kwargs): # real signature unknown
""" Return self<value. """
pass def __mul__(self, *args, **kwargs): # real signature unknown
""" Return self*value.n """
pass @staticmethod # known case of __new__
def __new__(*args, **kwargs): # real signature unknown
""" Create and return a new object. See help(type) for accurate signature. """
pass def __ne__(self, *args, **kwargs): # real signature unknown
""" Return self!=value. """
pass def __repr__(self, *args, **kwargs): # real signature unknown
""" Return repr(self). """
pass def __reversed__(self): # real signature unknown; restored from __doc__
""" L.__reversed__() -- return a reverse iterator over the list """
pass def __rmul__(self, *args, **kwargs): # real signature unknown
""" Return self*value. """
pass def __setitem__(self, *args, **kwargs): # real signature unknown
""" Set self[key] to value. """
pass def __sizeof__(self): # real signature unknown; restored from __doc__
""" L.__sizeof__() -- size of L in memory, in bytes """
pass __hash__ = None
查看
2.2.4 元组
定义：与列表类似，只不过［］改成（）
特性：
1.可存放多个值
2.不可变
3.按照从左到右的顺序定义元组元素，下标从0开始顺序访问，有序
2.2.4.1 元组创建
ages = (11, 22, 33, 44, 55)
或
ages = tuple((11, 22, 33, 44, 55))
2.2.4.2 元组常用操作
索引
切片
循环
长度
包含
2.2.4.3 元组工厂函数tuple()
2.2.5 字典
定义：｛key1:value1,key2:value2｝,key-value结构，key必须可hash
特性：
1.可存放多个值
2.可修改指定key对应的值，可变
3.无序
2.2.5.1 字典创建
person = {"name": "sb", 'age': 18}
或
person = dict(name='sb', age=18)
person = dict({"name": "sb", 'age': 18})
person = dict((['name','sb'],['age',18]))
{}.fromkeys(seq,100) #不指定100默认为None
注意：
>>> dic={}.fromkeys(['k1','k2'],[])
>>> dic
{'k1': [], 'k2': []}
>>> dic['k1'].append(1)
>>> dic
{'k1': [1], 'k2': [1]}
2.2.5.2 字典常用操作
索引
新增
删除
键、值、键值对
循环
长度
2.2.5.3 字典工厂函数dict()
2.2.6 集合
定义：由不同元素组成的集合，集合中是一组无序排列的可hash值，可以作为字典的key
特性：
1.集合的目的是将不同的值存放到一起，不同的集合间用来做关系运算，无需纠结于集合中单个值
2.2.6.1 集合创建
{1,2,3,1}
或
定义可变集合set
>>> set_test=set('hello')
>>> set_test
{'l', 'o', 'e', 'h'}
改为不可变集合frozenset
>>> f_set_test=frozenset(set_test)
>>> f_set_test
frozenset({'l', 'e', 'h', 'o'})
2.2.6.2 集合常用操作：关系运算
in
not in
＝＝
！＝
<,<=
>,>=
|,|=:合集
&.&=:交集
－,－=:差集
^,^=:对称差分
2.2.6.3 集合工厂函数set()
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
"""
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
"""
相当于s1-s2 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
""" Remove all elements of another set from this set. """
pass def discard(self, *args, **kwargs): # real signature unknown
"""
与remove功能相同，删除元素不存在时不会抛出异常 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
"""
相当于s1&s2 Return the intersection of two sets as a new set. (i.e. all elements that are in both sets.)
"""
pass def intersection_update(self, *args, **kwargs): # real signature unknown
""" Update a set with the intersection of itself and another. """
pass def isdisjoint(self, *args, **kwargs): # real signature unknown
""" Return True if two sets have a null intersection. """
pass def issubset(self, *args, **kwargs): # real signature unknown
"""
相当于s1<=s2 Report whether another set contains this set. """
pass def issuperset(self, *args, **kwargs): # real signature unknown
"""
相当于s1>=s2 Report whether this set contains another set. """
pass def pop(self, *args, **kwargs): # real signature unknown
"""
Remove and return an arbitrary set element.
Raises KeyError if the set is empty.
"""
pass def remove(self, *args, **kwargs): # real signature unknown
"""
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
"""
相当于s1^s2 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
""" Update a set with the symmetric difference of itself and another. """
pass def union(self, *args, **kwargs): # real signature unknown
"""
相当于s1|s2 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
""" Update a set with the union of itself and others. """
pass def __and__(self, *args, **kwargs): # real signature unknown
""" Return self&value. """
pass def __contains__(self, y): # real signature unknown; restored from __doc__
""" x.__contains__(y) <==> y in x. """
pass def __eq__(self, *args, **kwargs): # real signature unknown
""" Return self==value. """
pass def __getattribute__(self, *args, **kwargs): # real signature unknown
""" Return getattr(self, name). """
pass def __ge__(self, *args, **kwargs): # real signature unknown
""" Return self>=value. """
pass def __gt__(self, *args, **kwargs): # real signature unknown
""" Return self>value. """
pass def __iand__(self, *args, **kwargs): # real signature unknown
""" Return self&=value. """
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, *args, **kwargs): # real signature unknown
""" Return self|=value. """
pass def __isub__(self, *args, **kwargs): # real signature unknown
""" Return self-=value. """
pass def __iter__(self, *args, **kwargs): # real signature unknown
""" Implement iter(self). """
pass def __ixor__(self, *args, **kwargs): # real signature unknown
""" Return self^=value. """
pass def __len__(self, *args, **kwargs): # real signature unknown
""" Return len(self). """
pass def __le__(self, *args, **kwargs): # real signature unknown
""" Return self<=value. """
pass def __lt__(self, *args, **kwargs): # real signature unknown
""" Return self<value. """
pass @staticmethod # known case of __new__
def __new__(*args, **kwargs): # real signature unknown
""" Create and return a new object. See help(type) for accurate signature. """
pass def __ne__(self, *args, **kwargs): # real signature unknown
""" Return self!=value. """
pass def __or__(self, *args, **kwargs): # real signature unknown
""" Return self|value. """
pass def __rand__(self, *args, **kwargs): # real signature unknown
""" Return value&self. """
pass def __reduce__(self, *args, **kwargs): # real signature unknown
""" Return state information for pickling. """
pass def __repr__(self, *args, **kwargs): # real signature unknown
""" Return repr(self). """
pass def __ror__(self, *args, **kwargs): # real signature unknown
""" Return value|self. """
pass def __rsub__(self, *args, **kwargs): # real signature unknown
""" Return value-self. """
pass def __rxor__(self, *args, **kwargs): # real signature unknown
""" Return value^self. """
pass def __sizeof__(self): # real signature unknown; restored from __doc__
""" S.__sizeof__() -> size of S in memory, in bytes """
pass def __sub__(self, *args, **kwargs): # real signature unknown
""" Return self-value. """
pass def __xor__(self, *args, **kwargs): # real signature unknown
""" Return self^value. """
pass __hash__ = None 查看
查看
2.2.7 bytes类型
定义：存8bit整数，数据基于网络传输或内存变量存储到硬盘时需要转成bytes类型,字符串前置b代表为bytes类型
>>> x
'hello sb'
>>> x.encode('gb2312')
b'hello sb'
2.2.8 数据类型转换内置函数汇总
注：真对acsii表unichr在python2.7中比chr的范围更大，python3.*中chr内置了unichar
三.运算符
1、算数运算：
2、比较运算：
3、赋值运算：
4、位运算：
注： ~ 举例： ~5 = -6 解释： 将二进制数+1之后乘以-1，即~x = -(x+1)，-(101 + 1) = -110
按位反转仅能用在数字前面。所以写成 3+~5 可以得到结果-3，写成3~5就出错了
5、逻辑运算：
and注解：
- 在Python 中，and 和 or 执行布尔逻辑演算，如你所期待的一样，但是它们并不返回布尔值；而是，返回它们实际进行比较的值之一。
- 在布尔上下文中从左到右演算表达式的值，如果布尔上下文中的所有值都为真，那么 and 返回最后一个值。
- 如果布尔上下文中的某个值为假，则 and 返回第一个假值
or注解：
- 使用 or 时，在布尔上下文中从左到右演算值，就像 and 一样。如果有一个值为真，or 立刻返回该值
- 如果所有的值都为假，or 返回最后一个假值
- 注意 or 在布尔上下文中会一直进行表达式演算直到找到第一个真值，然后就会忽略剩余的比较值
and-or结合使用：
- 结合了前面的两种语法，推理即可。
- 为加强程序可读性，最好与括号连用，例如：
（1 and 'x') or 'y'
6、成员运算：
7.身份运算
8.运算符优先级：自上而下，优先级从高到低
四.标准数据类型特性总结
按存值个数区分
| 标量／原子类型 | 数字，字符串 |
| 容器类型 | 列表，元组，字典 |
按可变不可变区分
| 可变 | 列表，字典 |
| 不可变 | 数字，字符串，元组 |
按访问顺序区分
| 直接访问 | 数字 |
| 顺序访问（序列类型） | 字符串，列表，元组 |
| key值访问（映射类型） | 字典 |
第三篇：python基础之数据类型与变量的更多相关文章
- 【0728 | 预习】第三篇 Python基础
第三篇 Python基础预习 Part 1 变量 一.什么是变量? 二.为什么要有变量? 三.定义变量 四.变量的组成 五.变量名的命名规范 六.变量名的两种风格 Part 2 常量 Part 3 P ...
- 第二篇.1、python基础之数据类型与变量
一.变量 1 什么是变量之声明变量 #变量名=变量值 age=18 gender1='male' gender2='female' 2 为什么要有变量 变量作用:“变”=>变化,“量”=> ...
- python学习第三天：python基础（数据类型和变量）
注释 以 # 开头的语句是注释,如,注释不会被编译运行: 格式 当语句以冒号:结尾时,缩进的语句视为代码块.按照约定俗成的管理,应该始终坚持使用4个空格的缩进(在文本编辑器中,需要设置把Tab自动转 ...
- Python基础之数据类型和变量
数据类型 计算机顾名思义就是可以做数学机器,可以处理各种数值,计算机还能处理文本.图形.音频.视频.网页等各种各样的数据,不同的数据是需要定义不同的数据类型的,在Python中,能够直接处理的数据 ...
- python基础之数据类型与变量
一.变量 1 什么是变量之声明变量 #变量名=变量值age=18gender1='male' gender2='female' 2 为什么要有变量 变量作用:"变"=>变化, ...
- Python基础（数据类型与变量、字符串和编码）
#!/usr/bin/env python3 # -*- coding: utf-8 -*- # name = 200 # if name > 100: # print(name,'大于100' ...
- Python基础之数据类型、变量、常量
数据类型 整数:任意大小的整数,十六进制用0x前缀 浮点数:浮点数也就是小数,科学计数法1.23x109就是1.23e9,0.000012可以写成1.2e-5 字符串:以单引号'或双引号"括 ...
- python教程1:Python基础之数据类型和变量、字符串和编码
视频链接:http://www.bilibili.com/video/av10730372/ 我是在Linux下玩python的,Linux下默认安装python,直接打个pyhon3就好了,pyth ...
- python基础之数据类型与变量patr2
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: ...
随机推荐
- andriod打开摄像头和打开相册
package com.example.yanlei.picture; import android.support.v7.app.AppCompatActivity; import android. ...
- 自定义PropertyGrid控件【转】
自定义PropertyGrid控件 这篇随笔其实是从别人博客上载录的.感觉很有价值,整理了一下放在了我自己的博客上,希望原作者不要介意. 可自定义PropertyGrid控件的属性.也可将属性名称显示 ...
- Java中字符串转为16进制表示
Java中字符串转为16进制表示 String str = "鲸"; char[] chars = "0123456789ABCDEF".toCharArray ...
- treeList获取目录下的所有文件
/// <summary>/// treeList获取目录下的所有文件/// </summary>public static void InitTreeListGetFiles ...
- Neutron网络入门
Neutron是OpenStack核心项目之中的一个,提供云计算环境下的虚拟网络功能.Neutron的功能日益强大,并在Horizon面板中已经集成该模块.作为Neutron的核心开发人员之中的一个. ...
- C# 操作摄像头
如有雷同,不胜荣幸,若转载,请注明 这个是大众普通方法,鉴于有网友和朋友问相同的问题.在这里将我的拙劣的代码关键部分贴出来.以便帮助很多其它的朋友们,不足之处甚多,我能够学习,交流,请教阁下 废话到此 ...
- HashSet中存方用户自己定义数据类型数据，重写equals方法和hashCode方法
import java.util.Set; import java.util.HashSet; public class SetTest { public static void main(Strin ...
- 苦逼IT才能看懂的笑话
这是苦逼IT才能看懂的笑话1.栈和队列的区别是啥? 吃多了拉就是队列:吃多了吐就是栈 2.世界上最遥远的距离不是生与死,而是你亲手制造的BUG就在你眼前,你却怎么都找不到她... 3.<c++程 ...
- win7自带照片查看器
win10如何找回自带的照片查看器 方法/步骤 1 首先,我们打开一个记事本,可以点击win+r打开运行框,然后在运行框中输入notepad.或者在桌面右键点击里面的新建,然后在新建中找到文本 ...
- 一些常用的shell
1 if语句 if语句的三种写法,注意[]的两个空格,else if 写法是elif,不要漏了fi结束 if [ xxx ] then fi if [ xxx ] then echo "&q ...