第三篇：python基礎之數據類型與變量

時間 2020-05-12

原文原文鏈接

閱讀目錄python

一.變量
二.數據類型
2.1 什麼是數據類型及數據類型分類
2.2 標準數據類型：
2.2.1 數字
2.2.1.1 整型:
2.2.1.2 長整型long：
2.2.1.3 布爾bool:
2.2.1.4 浮點數float:
2.2.1.5 複數complex:
2.2.1.6 數字相關內建函數
2.2.2 字符串
2.2.2.1 字符串建立
2.2.2.2 字符串經常使用操做
2.2.2.3 字符工廠函數str()
2.2.3 列表
2.2.3.1 列表建立
2.2.3.2 列表經常使用操做
2.2.3.3 列表工廠函數list()
2.2.4 元組
2.2.4.1 元組建立
2.2.4.2 元組經常使用操做
2.2.4.3 元組工廠函數tuple()
2.2.5 字典
2.2.5.1 字典建立
2.2.5.2 字典經常使用操做
2.2.5.3 字典工廠函數dict()
2.2.6 集合
2.2.6.1 集合建立
2.2.6.2 集合經常使用操做：關係運算
2.2.6.3 集合工廠函數set()
2.2.7 bytes類型
2.2.8 數據類型轉換內置函數彙總
三.運算符
四.標準數據類型特性總結

一.變量

1 什麼是變量之聲明變量

#變量名=變量值
age=18 gender1='male' gender2='female'

2 爲何要有變量

變量做用：「變」=>變化，「量」=>計量/保存狀態
程序的運行本質是一系列狀態的變化，變量的目的就是用來保存狀態，變量值的變化就構成了程序運行的不一樣結果。
例如：CS槍戰，一我的的生命能夠表示爲life＝active表示存活，當知足某種條件後修改變量life＝inactive表示死亡。
3 變量值之類型與對象
程序中須要處理的狀態不少，因而有了不一樣類型的變量值，x='egon',變量值'egon'存放與內存中，綁定一個名字x，變量值即咱們要存儲的數據。

在python中全部數據都是圍繞對象這個概念來構建的，對象包含一些基本的數據類型：數字，字符串，列表，元組，字典等
程序中存儲的全部數據都是對象，
一個對象（如a=1）有：
　　一個身份（id）
　　一個類型(type)
　　一個值(經過變量名a來查看)
1 對象的類型也稱爲對象的類別，python爲每一個類型都定製了屬於該類型特有的方法，極大地方便了開發者對數據的處理
2 建立某個特定類型的對象也稱爲建立了該類型的一個實例，工廠函數的概念來源於此
4 可變對象與不可變對象
實例被建立後，身份和類型是不可變的，
若是值是不能夠被修改的，則是不可變對象
若是值是能夠被修改的，則是可變對象

5 容器對象
某個對象包含對其餘對象的引用，則稱爲容器或集合

6 對象的屬性和方法
屬性就是對象的值，方法就是調用時將在對象自己上執行某些操做的函數，使用.運算符能夠訪問對象的屬性和方法，如
a=3+4j
a.real

b=[1,2,3]
b.append(4)

7 身份比較，類型比較，值比較
x=1
y=1
x is y #x與y是同一個對象，is比較的是id，即身份
type(x) is type(y) #對象的類型自己也是一個對象，因此能夠用is比較兩個對象的類型的身份
x == y #==比較的是兩個對象的值是否相等


7 變量的命名規範

變量命名規則遵循標識符命名規則，詳見第二篇

8 變量的賦值操做git

與c語言的區別在於變量賦值操做無返回值
鏈式賦值：y＝x＝a＝1
多元賦值：x,y=1,2 x,y=y,x
增量賦值：x+=1

二.數據類型

2.1 什麼是數據類型及數據類型分類

程序的本質就是驅使計算機去處理各類狀態的變化，這些狀態分爲不少種

例如英雄聯盟遊戲，一我的物角色有名字，錢，等級，裝備等特性，你們第一時間會想到這麼表示
名字：德瑪西亞－－－－－－－－－－－－>字符串
錢：10000   －－－－－－－－－－－－>數字
等級：15    －－－－－－－－－－－－>數字
裝備：鞋子，日炎斗篷，蘭頓之兆－－－－>列表
(記錄這些人物特性的是變量，這些特性的真實存在則是變量的值，存不一樣的特性須要用不一樣類型的值)

python中的數據類型
python使用對象模型來存儲數據，每個數據類型都有一個內置的類，每新建一個數據，實際就是在初始化生成一個對象，即全部數據都是對象
對象三個特性

身份：內存地址，能夠用id()獲取
類型：決定了該對象能夠保存什麼類型值，可執行何種操做，需遵循什麼規則，可用type()獲取
值：對象保存的真實數據

注：咱們在定義數據類型，只需這樣：x＝1，內部生成1這一內存對象會自動觸發，咱們無需關心


這裏的字符串、數字、列表等都是數據類型（用來描述某種狀態或者特性）除此以外還有不少其餘數據，處理不一樣的數據就須要定義不一樣的數據類型

標準類型	其餘類型
數字	類型type
字符串	Null
列表	文件
元組	集合
字典	函數／方法
	類
	模塊

2.2 標準數據類型：

2.2.1 數字

定義：a＝1api

特性：數組

1.只能存放一個值網絡

2.一經定義，不可更改app

3.直接訪問less

分類：整型，長整型，布爾，浮點，複數python2.7

2.2.1.1 整型:

Python的整型至關於C中的long型,Python中的整數能夠用十進制,八進制,十六進制表示。ide

>>> 10
10         --------->默認十進制 >>> oct(10) '012'      --------->八進制表示整數時，數值前面要加上一個前綴「0」 >>> hex(10) '0xa'      --------->十六進制表示整數時，數字前面要加上前綴0X或0x

python2.*與python3.*關於整型的區別函數

python2.*
在32位機器上，整數的位數爲32位，取值範圍爲-2**31～2**31-1，即-2147483648～2147483647

在64位系統上，整數的位數爲64位，取值範圍爲-2**63～2**63-1，即-9223372036854775808～9223372036854775807
python3.*整形長度無限制

整型工廠函數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): """ 返回表示該數字的時佔用的最少位數 """
        """ 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
        """ 返回該複數的共軛複數 """
        """ Returns self, the complex conjugate of any int. """
        pass

    def __abs__(self): """ 返回絕對值 """
        """ 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): """ 比較兩個數大小 """
        """ x.__cmp__(y) <==> cmp(x,y) """
        pass

    def __coerce__(self, y): """ 強制生成一個元組 """ 
        """ x.__coerce__(y) <==> coerce(x, y) """
        pass

    def __divmod__(self, y): """ 相除，獲得商和餘數組成的元組 """ 
        """ x.__divmod__(y) <==> divmod(x, y) """
        pass

    def __div__(self, y): """ x.__div__(y) <==> x/y """
        pass

    def __float__(self): """ 轉換爲浮點類型 """ 
        """ 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
        """ 內部調用 __new__方法或建立對象時傳入參數使用 """ 
        pass

    def __hash__(self): """若是對象object爲哈希表類型，返回對象object的哈希值。哈希值爲整數。在字典查找中，哈希值用於快速比較字典的鍵。兩個數值若是相等，則哈希值也相等。"""
        """ x.__hash__() <==> hash(x) """
        pass

    def __hex__(self): """ 返回當前數的 十六進制 表示 """ 
        """ x.__hex__() <==> hex(x) """
        pass

    def __index__(self): """ 用於切片，數字無心義 """
        """ x[y:z] <==> x[y.__index__():z.__index__()] """
        pass

    def __init__(self, x, base=10): # known special case of int.__init__
        """ 構造方法，執行 x = 123 或 x = int(10) 時，自動調用，暫時忽略 """ 
        """ 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): """ 轉換爲整數 """ 
        """ x.__int__() <==> int(x) """
        pass

    def __invert__(self): """ x.__invert__() <==> ~x """
        pass

    def __long__(self): """ 轉換爲長整數 """ 
        """ 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 八進制 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): """ 冪，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): """轉化爲解釋器可讀取的形式 """
        """ x.__repr__() <==> repr(x) """
        pass

    def __str__(self): """轉換爲人閱讀的形式，若是沒有適於人閱讀的解釋形式的話，則返回解釋器課閱讀的形式"""
        """ 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): """ 返回數值被截取爲整形的值，在整形中無心義 """
        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
    """ 虛數，無心義 """
    """the imaginary part of a complex number""" numerator = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 分子 = 數字大小 """
    """the numerator of a rational number in lowest terms""" real = property(lambda self: object(), lambda self, v: None, lambda self: None)  # default
    """ 實屬，無心義 """
    """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__
        """ 返回表示該數字的時佔用的最少位數 """
        """ 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
        """ 返回該複數的共軛複數 """
        """ 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
        """ 整數返回本身 若是是小數 math.ceil(3.1)返回4 """
        """ Ceiling of an Integral returns itself. """
        pass

    def __divmod__(self, *args, **kwargs): # real signature unknown
        """ 相除，獲得商和餘數組成的元組 """
        """ 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
        """ 用於切片，數字無心義 """
        """ 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__
        """ 構造方法，執行 x = 123 或 x = int(10) 時，自動調用，暫時忽略 """
        """ 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 長整型long：

python2.*：
跟C語言不一樣，Python的長整型沒有指定位寬，也就是說Python沒有限制長整型數值的大小，
可是實際上因爲機器內存有限，因此咱們使用的長整型數值不可能無限大。
在使用過程當中，咱們如何區分長整型和整型數值呢？
一般的作法是在數字尾部加上一個大寫字母L或小寫字母l以表示該整數是長整型的，例如：
a = 9223372036854775808L
注意，自從Python2起，若是發生溢出，Python會自動將整型數據轉換爲長整型，
因此現在在長整型數據後面不加字母L也不會致使嚴重後果了。

python3.*
長整型，整型統一歸爲整型

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 布爾bool:

True 和False
1和0

2.2.1.4 浮點數float:

Python的浮點數就是數學中的小數，相似C語言中的double。
在運算中，整數與浮點數運算的結果是浮點數
浮點數也就是小數，之因此稱爲浮點數，是由於按照科學記數法表示時，
一個浮點數的小數點位置是可變的，好比，1.23*109和12.3*108是相等的。
浮點數能夠用數學寫法，如1.23，3.14，-9.01，等等。可是對於很大或很小的浮點數，
就必須用科學計數法表示，把10用e替代，1.23*109就是1.23e9，或者12.3e8，0.000012
能夠寫成1.2e-5，等等。
整數和浮點數在計算機內部存儲的方式是不一樣的，整數運算永遠是精確的而浮點數運算則可能會有
四捨五入的偏差。

2.2.1.5 複數complex:

複數由實數部分和虛數部分組成，通常形式爲x＋yj，其中的x是複數的實數部分，y是複數的虛數部分，這裏的x和y都是實數。
注意，虛數部分的字母j大小寫均可以，

>>> 1.3 + 2.5j == 1.3 + 2.5J True

2.2.1.6 數字相關內建函數

2.2.2 字符串

定義：它是一個有序的字符的集合，用於存儲和表示基本的文本信息，‘’或「」或‘’‘ ’‘’中間包含的內容稱之爲字符串
特性：
1.只能存放一個值
2.不可變
3.按照從左到右的順序定義字符集合，下標從0開始順序訪問，有序
補充：
　　1.字符串的單引號和雙引號都沒法取消特殊字符的含義，若是想讓引號內全部字符均取消特殊意義，在引號前面加r，如name＝r'l\thf'
　　2.unicode字符串與r連用必需在r前面，如name＝ur'l\thf'

2.2.2.1 字符串建立

‘hello world’

2.2.2.2 字符串經常使用操做

移除空白
分割
長度
索引
切片

2.2.2.3 字符工廠函數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__
        """ 首字母變大寫 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__
        """ 原來字符居中，不夠用空格補全 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__
        """ 從一個範圍內的統計某str出現次數 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指定編碼格式編碼，若是出錯默認報一個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__
        """ 將字符串中包含的\t轉換成tabsize個空格 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
        """ 格式化輸出 三種形式： 形式一. >>> print('{0}{1}{0}'.format('a','b')) aba 形式二：（必須一一對應） >>> 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__
        """ 與format區別 '{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__
        """ 至少一個字符，且都是字母或數字才返回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__
        """ 至少一個字符，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__
        """ 字符串爲關鍵字返回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__
        """ 至少一個字符，且都是小寫字母才返回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__
        """ 至少一個字符，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__
        """ #對序列進行操做（分別使用' '與':'做爲分隔符） >>> seq1 = ['hello','good','boy','doiido'] >>> print ' '.join(seq1) hello good boy doiido >>> print ':'.join(seq1) hello:good:boy:doiido #對字符串進行操做 >>> 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 #對元組進行操做 >>> seq3 = ('hello','good','boy','doiido') >>> print ':'.join(seq3) hello:good:boy:doiido #對字典進行操做 >>> seq4 = {'hello':1,'good':2,'boy':3,'doiido':4} >>> print ':'.join(seq4) boy:good:doiido:hello #合併目錄 >>> 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爲分割，將S分紅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爲分割，將S切分紅列表，與partition的區別在於切分結果不包含sep， 若是一個字符串中包含多個sep那麼maxsplit爲最多切分紅幾部分 >>> 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， 返回一個包含各行做爲元素的列表，若是參數 keepends 爲 False，不包含換行符，如 果爲 True，則保留換行符。 >>> 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__
        """ 大小寫反轉 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__
        """ 原來字符右對齊，不夠用0補齊 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 字符串工廠函數

字符串工廠函數

num = "1"  #unicode
num.isdigit()   # True
num.isdecimal() # True
num.isnumeric() # True
 num = "1" # 全角
num.isdigit()   # True
num.isdecimal() # True
num.isnumeric() # True
 num = b"1" # byte
num.isdigit()   # True
num.isdecimal() # AttributeError 'bytes' object has no attribute 'isdecimal'
num.isnumeric() # AttributeError 'bytes' object has no attribute 'isnumeric'
 num = "IV" # 羅馬數字
num.isdigit()   # True
num.isdecimal() # False
num.isnumeric() # True
 num = "四" # 漢字
num.isdigit()   # False
num.isdecimal() # False
num.isnumeric() # True

=================== isdigit() True: Unicode數字，byte數字（單字節），全角數字（雙字節），羅馬數字 False: 漢字數字 Error: 無 isdecimal() True: Unicode數字，，全角數字（雙字節） False: 羅馬數字，漢字數字 Error: byte數字（單字節） isnumeric() True: Unicode數字，全角數字（雙字節），羅馬數字，漢字數字 False: 無 Error: byte數字（單字節） ================
import unicodedata unicodedata.digit("2")   # 2
unicodedata.decimal("2") # 2
unicodedata.numeric("2") # 2.0
 unicodedata.digit("2")   # 2
unicodedata.decimal("2") # 2
unicodedata.numeric("2") # 2.0
 unicodedata.digit(b"3")   # TypeError: must be str, not bytes
unicodedata.decimal(b"3") # TypeError: must be str, not bytes
unicodedata.numeric(b"3") # 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","參","四","五","六","七","八","九","十","廿","卅","卌","百","千","萬","萬","億"

python中str函數isdigit、isdecimal、isnumeric的區別

2.2.3 列表

定義：[]內以逗號分隔，按照索引，存放各類數據類型，每一個位置表明一個元素
特性：
1.可存放多個值
2.可修改指定索引位置對應的值，可變
3.按照從左到右的順序定義列表元素，下標從0開始順序訪問，有序

2.2.3.1 列表建立

list_test=[’lhf‘,12,'ok']
或
list_test=list('abc')
或
list_test=list([’lhf‘,12,'ok'])

2.2.3.2 列表經常使用操做

索引
切片
追加
刪除
長度
切片
循環
包含

2.2.3.3 列表工廠函數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 元組

定義：與列表相似，只不過［］改爲（）
特性：

1.可存放多個值
2.不可變
3.按照從左到右的順序定義元組元素，下標從0開始順序訪問，有序

2.2.4.1 元組建立

ages = (11, 22, 33, 44, 55)
或
ages = tuple((11, 22, 33, 44, 55))

2.2.4.2 元組經常使用操做

索引
切片
循環
長度
包含

2.2.4.3 元組工廠函數tuple()

2.2.5 字典

定義：｛key1:value1,key2:value2｝,key-value結構，key必須可hash
特性：

1.可存放多個值
2.可修改指定key對應的值，可變
3.無序

2.2.5.1 字典建立

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默認爲None
注意：

>>> dic={}.fromkeys(['k1','k2'],[]) >>> dic {'k1': [], 'k2': []} >>> dic['k1'].append(1) >>> dic {'k1': [1], 'k2': [1]}

2.2.5.2 字典經常使用操做

索引
新增
刪除
鍵、值、鍵值對
循環
長度

2.2.5.3 字典工廠函數dict()

2.2.6 集合

定義：由不一樣元素組成的集合，集合中是一組無序排列的可hash值，能夠做爲字典的key
特性：
1.集合的目的是將不一樣的值存放到一塊兒，不一樣的集合間用來作關係運算，無需糾結於集合中單個值

2.2.6.1 集合建立

{1,2,3,1}
或
定義可變集合set
>>> set_test=set('hello')
>>> set_test
{'l', 'o', 'e', 'h'}
改成不可變集合frozenset
>>> f_set_test=frozenset(set_test)
>>> f_set_test
frozenset({'l', 'e', 'h', 'o'})

2.2.6.2 集合經常使用操做：關係運算

　　 in
    not in
    ＝＝
    ！＝
    <,<=
    >,>=
    |,|=:合集
    &.&=:交集
    －,－=:差集
    ^,^=:對稱差分

2.2.6.3 集合工廠函數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
        """ 至關於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
        """ 與remove功能相同，刪除元素不存在時不會拋出異常 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
        """ 至關於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
        """ 至關於s1<=s2 Report whether another set contains this set. """
        pass

    def issuperset(self, *args, **kwargs): # real signature unknown
        """ 至關於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
        """ 至關於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
        """ 至關於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類型

定義：存8bit整數，數據基於網絡傳輸或內存變量存儲到硬盤時須要轉成bytes類型,字符串前置b表明爲bytes類型

>>> x 'hello sb'
>>> x.encode('gb2312') b'hello sb'

2.2.8 數據類型轉換內置函數彙總

注：真對acsii表unichr在python2.7中比chr的範圍更大，python3.*中chr內置了unichar

三.運算符

一、算數運算：

二、比較運算：

三、賦值運算：

四、位運算：

注： ~ 舉例： ~5 = -6 解釋：將二進制數+1以後乘以-1，即~x = -(x+1)，-(101 + 1) = -110

按位反轉僅能用在數字前面。因此寫成 3+~5 能夠獲得結果-3，寫成3~5就出錯了

五、邏輯運算：

and註解：

在Python 中，and 和 or 執行布爾邏輯演算，如你所期待的同樣，可是它們並不返回布爾值；而是，返回它們實際進行比較的值之一。
在布爾上下文中從左到右演算表達式的值，若是布爾上下文中的全部值都爲真，那麼 and 返回最後一個值。
若是布爾上下文中的某個值爲假，則 and 返回第一個假值

or註解：

使用 or 時，在布爾上下文中從左到右演算值，就像 and 同樣。若是有一個值爲真，or 馬上返回該值
若是全部的值都爲假，or 返回最後一個假值
注意 or 在布爾上下文中會一直進行表達式演算直到找到第一個真值，而後就會忽略剩餘的比較值

and-or結合使用：

結合了前面的兩種語法，推理便可。
爲增強程序可讀性，最好與括號連用，例如：
```
（1 and 'x') or 'y'
```

六、成員運算：

7.身份運算

8.運算符優先級：自上而下，優先級從高到低

四.標準數據類型特性總結

按存值個數區分

標量／原子類型	數字，字符串
容器類型	列表，元組，字典

按可變不可變區分

可變	列表，字典
不可變	數字，字符串，元組

按訪問順序區分

直接訪問	數字
順序訪問（序列類型）	字符串，列表，元組
key值訪問（映射類型）	字典

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