python基础-第二篇-基本数据类型
一.运算符
1、算数运算：
算数运算符相信大家都不陌生吧，尤其是加减乘除，好！那我就带着大家看看最后三个，这三个到底是干什么玩意的？
- %，取两数相除的余数，看图：
- **，x的多少次幂，看图：
- //，取整除，你可以理解为向下取整，看图：
2、比较运算：
注意：当为一个等号时，多为赋值，两个等号为比较，另外不等于常用是！=
3、赋值运算：
4、逻辑运算：
逻辑运算符里，and和or好理解，那我就讲一下not：这家伙就是唱反调的--看图
5、成员运算：
成员运算符，从字面上意思去理解，问谁是不是某组织里的一份子，好！例子说话
二.基本数据类型
- 对象是基于类创建的，对象的功能或方法都在类里
- python里的基本数据类型--int，str，list，dict，tuple都是类
- 类是抽象的，对象则是具体的，所以只有类-对象化，才可使用类的方法
- 查看类或对象的所有方法：dir（对象）--查看功能， help（类）--详细， ctrl + 左键（pycharm里）
1.int（整型）
- 在32位机器上，整数的位数为32位，取值范围为-2**31～2**31-1，即-2147483648～2147483647
- 在64位系统上，整数的位数为64位，取值范围为-2**63～2**63-1，即-9223372036854775808～922337203685477580
class int(object): """ int(x=0) -> int or long int(x, base=10) -> int or long Convert a number or string to an integer, or return 0 if no arguments are given. If x is floating point, the conversion truncates towards zero. If x is outside the integer range, the function returns a long instead. If x is not a number or if base is given, then x must be a string or Unicode object representing an integer literal in the given base. The literal can be preceded by '+' or '-' and be surrounded by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to interpret the base from the string as an integer literal. >>> int('0b100', base=0) 4 """ def bit_length(self): """ 返回表示该数字的时占用的最少位数 """ """ int.bit_length() -> int Number of bits necessary to represent self in binary. >>> bin(37) '0b100101' >>> (37).bit_length() 6 """ return 0 def conjugate(self, *args, **kwargs): # real signature unknown """ 返回该复数的共轭复数 """ """ Returns self, the complex conjugate of any int. """ pass def __abs__(self): """ 返回绝对值 """ """ x.__abs__() <==> abs(x) """ pass def __add__(self, y): """ x.__add__(y) <==> x+y """ pass def __and__(self, y): """ x.__and__(y) <==> x&y """ pass def __cmp__(self, y): """ 比较两个数大小 """ """ x.__cmp__(y) <==> cmp(x,y) """ pass def __coerce__(self, y): """ 强制生成一个元组 """ """ x.__coerce__(y) <==> coerce(x, y) """ pass def __divmod__(self, y): """ 相除，得到商和余数组成的元组 """ """ x.__divmod__(y) <==> divmod(x, y) """ pass def __div__(self, y): """ x.__div__(y) <==> x/y """ pass def __float__(self): """ 转换为浮点类型 """ """ x.__float__() <==> float(x) """ pass def __floordiv__(self, y): """ x.__floordiv__(y) <==> x//y """ pass def __format__(self, *args, **kwargs): # real signature unknown pass def __getattribute__(self, name): """ x.__getattribute__('name') <==> x.name """ pass def __getnewargs__(self, *args, **kwargs): # real signature unknown """ 内部调用 __new__方法或创建对象时传入参数使用 """ pass def __hash__(self): """如果对象object为哈希表类型，返回对象object的哈希值。哈希值为整数。在字典查找中，哈希值用于快速比较字典的键。两个数值如果相等，则哈希值也相等。""" """ x.__hash__() <==> hash(x) """ pass def __hex__(self): """ 返回当前数的 十六进制 表示 """ """ x.__hex__() <==> hex(x) """ pass def __index__(self): """ 用于切片，数字无意义 """ """ x[y:z] <==> x[y.__index__():z.__index__()] """ pass def __init__(self, x, base=10): # known special case of int.__init__ """ 构造方法，执行 x = 123 或 x = int(10) 时，自动调用，暂时忽略 """ """ int(x=0) -> int or long int(x, base=10) -> int or long Convert a number or string to an integer, or return 0 if no arguments are given. If x is floating point, the conversion truncates towards zero. If x is outside the integer range, the function returns a long instead. If x is not a number or if base is given, then x must be a string or Unicode object representing an integer literal in the given base. The literal can be preceded by '+' or '-' and be surrounded by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to interpret the base from the string as an integer literal. >>> int('0b100', base=0) 4 # (copied from class doc) """ pass def __int__(self): """ 转换为整数 """ """ x.__int__() <==> int(x) """ pass def __invert__(self): """ x.__invert__() <==> ~x """ pass def __long__(self): """ 转换为长整数 """ """ x.__long__() <==> long(x) """ pass def __lshift__(self, y): """ x.__lshift__(y) <==> x<<y """ pass def __mod__(self, y): """ x.__mod__(y) <==> x%y """ pass def __mul__(self, y): """ x.__mul__(y) <==> x*y """ pass def __neg__(self): """ x.__neg__() <==> -x """ pass @staticmethod # known case of __new__ def __new__(S, *more): """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ pass def __nonzero__(self): """ x.__nonzero__() <==> x != 0 """ pass def __oct__(self): """ 返回改值的 八进制 表示 """ """ x.__oct__() <==> oct(x) """ pass def __or__(self, y): """ x.__or__(y) <==> x|y """ pass def __pos__(self): """ x.__pos__() <==> +x """ pass def __pow__(self, y, z=None): """ 幂，次方 """ """ x.__pow__(y[, z]) <==> pow(x, y[, z]) """ pass def __radd__(self, y): """ x.__radd__(y) <==> y+x """ pass def __rand__(self, y): """ x.__rand__(y) <==> y&x """ pass def __rdivmod__(self, y): """ x.__rdivmod__(y) <==> divmod(y, x) """ pass def __rdiv__(self, y): """ x.__rdiv__(y) <==> y/x """ pass def __repr__(self): """转化为解释器可读取的形式 """ """ x.__repr__() <==> repr(x) """ pass def __str__(self): """转换为人阅读的形式，如果没有适于人阅读的解释形式的话，则返回解释器课阅读的形式""" """ x.__str__() <==> str(x) """ pass def __rfloordiv__(self, y): """ x.__rfloordiv__(y) <==> y//x """ pass def __rlshift__(self, y): """ x.__rlshift__(y) <==> y<<x """ pass def __rmod__(self, y): """ x.__rmod__(y) <==> y%x """ pass def __rmul__(self, y): """ x.__rmul__(y) <==> y*x """ pass def __ror__(self, y): """ x.__ror__(y) <==> y|x """ pass def __rpow__(self, x, z=None): """ y.__rpow__(x[, z]) <==> pow(x, y[, z]) """ pass def __rrshift__(self, y): """ x.__rrshift__(y) <==> y>>x """ pass def __rshift__(self, y): """ x.__rshift__(y) <==> x>>y """ pass def __rsub__(self, y): """ x.__rsub__(y) <==> y-x """ pass def __rtruediv__(self, y): """ x.__rtruediv__(y) <==> y/x """ pass def __rxor__(self, y): """ x.__rxor__(y) <==> y^x """ pass def __sub__(self, y): """ x.__sub__(y) <==> x-y """ pass def __truediv__(self, y): """ x.__truediv__(y) <==> x/y """ pass def __trunc__(self, *args, **kwargs): """ 返回数值被截取为整形的值，在整形中无意义 """ pass def __xor__(self, y): """ x.__xor__(y) <==> x^y """ pass denominator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default """ 分母 = 1 """ """the denominator of a rational number in lowest terms""" imag = property(lambda self: object(), lambda self, v: None, lambda self: None) # default """ 虚数，无意义 """ """the imaginary part of a complex number""" numerator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default """ 分子 = 数字大小 """ """the numerator of a rational number in lowest terms""" real = property(lambda self: object(), lambda self, v: None, lambda self: None) # default """ 实属，无意义 """ """the real part of a complex number""" - 你不用担心数值超过int的长度，python会自动转化long（长整）
class int(object): """ int(x=0) -> int or long int(x, base=10) -> int or long Convert a number or string to an integer, or return 0 if no arguments are given. If x is floating point, the conversion truncates towards zero. If x is outside the integer range, the function returns a long instead. If x is not a number or if base is given, then x must be a string or Unicode object representing an integer literal in the given base. The literal can be preceded by '+' or '-' and be surrounded by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to interpret the base from the string as an integer literal. >>> int('0b100', base=0) 4 """ def bit_length(self): """ 返回表示该数字的时占用的最少位数 """ """ int.bit_length() -> int Number of bits necessary to represent self in binary. >>> bin(37) '0b100101' >>> (37).bit_length() 6 """ return 0 def conjugate(self, *args, **kwargs): # real signature unknown """ 返回该复数的共轭复数 """ """ Returns self, the complex conjugate of any int. """ pass def __abs__(self): """ 返回绝对值 """ """ x.__abs__() <==> abs(x) """ pass def __add__(self, y): """ x.__add__(y) <==> x+y """ pass def __and__(self, y): """ x.__and__(y) <==> x&y """ pass def __cmp__(self, y): """ 比较两个数大小 """ """ x.__cmp__(y) <==> cmp(x,y) """ pass def __coerce__(self, y): """ 强制生成一个元组 """ """ x.__coerce__(y) <==> coerce(x, y) """ pass def __divmod__(self, y): """ 相除，得到商和余数组成的元组 """ """ x.__divmod__(y) <==> divmod(x, y) """ pass def __div__(self, y): """ x.__div__(y) <==> x/y """ pass def __float__(self): """ 转换为浮点类型 """ """ x.__float__() <==> float(x) """ pass def __floordiv__(self, y): """ x.__floordiv__(y) <==> x//y """ pass def __format__(self, *args, **kwargs): # real signature unknown pass def __getattribute__(self, name): """ x.__getattribute__('name') <==> x.name """ pass def __getnewargs__(self, *args, **kwargs): # real signature unknown """ 内部调用 __new__方法或创建对象时传入参数使用 """ pass def __hash__(self): """如果对象object为哈希表类型，返回对象object的哈希值。哈希值为整数。在字典查找中，哈希值用于快速比较字典的键。两个数值如果相等，则哈希值也相等。""" """ x.__hash__() <==> hash(x) """ pass def __hex__(self): """ 返回当前数的 十六进制 表示 """ """ x.__hex__() <==> hex(x) """ pass def __index__(self): """ 用于切片，数字无意义 """ """ x[y:z] <==> x[y.__index__():z.__index__()] """ pass def __init__(self, x, base=10): # known special case of int.__init__ """ 构造方法，执行 x = 123 或 x = int(10) 时，自动调用，暂时忽略 """ """ int(x=0) -> int or long int(x, base=10) -> int or long Convert a number or string to an integer, or return 0 if no arguments are given. If x is floating point, the conversion truncates towards zero. If x is outside the integer range, the function returns a long instead. If x is not a number or if base is given, then x must be a string or Unicode object representing an integer literal in the given base. The literal can be preceded by '+' or '-' and be surrounded by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to interpret the base from the string as an integer literal. >>> int('0b100', base=0) 4 # (copied from class doc) """ pass def __int__(self): """ 转换为整数 """ """ x.__int__() <==> int(x) """ pass def __invert__(self): """ x.__invert__() <==> ~x """ pass def __long__(self): """ 转换为长整数 """ """ x.__long__() <==> long(x) """ pass def __lshift__(self, y): """ x.__lshift__(y) <==> x<<y """ pass def __mod__(self, y): """ x.__mod__(y) <==> x%y """ pass def __mul__(self, y): """ x.__mul__(y) <==> x*y """ pass def __neg__(self): """ x.__neg__() <==> -x """ pass @staticmethod # known case of __new__ def __new__(S, *more): """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ pass def __nonzero__(self): """ x.__nonzero__() <==> x != 0 """ pass def __oct__(self): """ 返回改值的 八进制 表示 """ """ x.__oct__() <==> oct(x) """ pass def __or__(self, y): """ x.__or__(y) <==> x|y """ pass def __pos__(self): """ x.__pos__() <==> +x """ pass def __pow__(self, y, z=None): """ 幂，次方 """ """ x.__pow__(y[, z]) <==> pow(x, y[, z]) """ pass def __radd__(self, y): """ x.__radd__(y) <==> y+x """ pass def __rand__(self, y): """ x.__rand__(y) <==> y&x """ pass def __rdivmod__(self, y): """ x.__rdivmod__(y) <==> divmod(y, x) """ pass def __rdiv__(self, y): """ x.__rdiv__(y) <==> y/x """ pass def __repr__(self): """转化为解释器可读取的形式 """ """ x.__repr__() <==> repr(x) """ pass def __str__(self): """转换为人阅读的形式，如果没有适于人阅读的解释形式的话，则返回解释器课阅读的形式""" """ x.__str__() <==> str(x) """ pass def __rfloordiv__(self, y): """ x.__rfloordiv__(y) <==> y//x """ pass def __rlshift__(self, y): """ x.__rlshift__(y) <==> y<<x """ pass def __rmod__(self, y): """ x.__rmod__(y) <==> y%x """ pass def __rmul__(self, y): """ x.__rmul__(y) <==> y*x """ pass def __ror__(self, y): """ x.__ror__(y) <==> y|x """ pass def __rpow__(self, x, z=None): """ y.__rpow__(x[, z]) <==> pow(x, y[, z]) """ pass def __rrshift__(self, y): """ x.__rrshift__(y) <==> y>>x """ pass def __rshift__(self, y): """ x.__rshift__(y) <==> x>>y """ pass def __rsub__(self, y): """ x.__rsub__(y) <==> y-x """ pass def __rtruediv__(self, y): """ x.__rtruediv__(y) <==> y/x """ pass def __rxor__(self, y): """ x.__rxor__(y) <==> y^x """ pass def __sub__(self, y): """ x.__sub__(y) <==> x-y """ pass def __truediv__(self, y): """ x.__truediv__(y) <==> x/y """ pass def __trunc__(self, *args, **kwargs): """ 返回数值被截取为整形的值，在整形中无意义 """ pass def __xor__(self, y): """ x.__xor__(y) <==> x^y """ pass denominator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default """ 分母 = 1 """ """the denominator of a rational number in lowest terms""" imag = property(lambda self: object(), lambda self, v: None, lambda self: None) # default """ 虚数，无意义 """ """the imaginary part of a complex number""" numerator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default """ 分子 = 数字大小 """ """the numerator of a rational number in lowest terms""" real = property(lambda self: object(), lambda self, v: None, lambda self: None) # default """ 实属，无意义 """ """the real part of a complex number"""
我们会看到有好多方法，还好多带两下划线的方法，你可能会想，这些我们都会经常用吗？
那我告诉这些带两下划线的方法基本不用，这些方法是python私有方法，让我们来看一个小例子就知道python怎么私有化的
str1 = 'you are ' str2 = 'very nice' result1 = str1.__add__(str2) print(result1) #结果为you are very nice result2 = str1 + str2 print(result2) #结果为you are very nice
好，两种方式的结果都是一样的，不过在python里，却是在执行第二种方式时调用了第一种方式
n1 = 123 print(n1) #结果为123 n2 = int(123) print(n2) #结果为123
看着上面的代码，我们可以知道根据int类，创建一个对象有两种方式，而本质上是在执行方式一时调用了方式二，然后方式二又去int的特有功能里找到__init__并执行了它（后面讲的基础数据类型都是这两种创建方式，内部调用原理也一样）
bit_length() 获取表示的二进制最短位数（什么？你看不懂？我讲的这么通俗易懂，你居然不懂？好吧，我讲的太官方了，看个小例子吧）
x = 2 result1 = x.bit_length() x = 15 result2 = x.bit_length() print(result1,result2,sep='---') #结果为2---4
看完例子懂了吧？2用二进制只要占两位，所以结果为2
刚才我们简单的提了一下__init__，其实它还有第二参数--设置进制的
a1 = int('0b101',2) print(a1) #结果为5
来，让你看一张奇图，id（）查看内存地址的方法
看到没有？怎么会有这样的结果？
结论就是：不同变量同一个数字要开辟两份内存空间，python对此进行了优化，让同一数字指向同一内存空间，节省内存，不过这也只适用-5-257，否则要用两份内存，另外，变量赋值给变量，拿n8 = n7说，这个赋值过程其实是n8先找到n7，在顺着n7找其对应2345的内存地址，所以它们的内存地址是一样的
2.布尔值
真或假
1 或 0
3.str(字符串)
class str(basestring): """ str(object='') -> string Return a nice string representation of the object. If the argument is a string, the return value is the same object. """ def capitalize(self): """ 首字母变大写 """ """ S.capitalize() -> string Return a copy of the string S with only its first character capitalized. """ return "" def center(self, width, fillchar=None): """ 内容居中，width：总长度；fillchar：空白处填充内容，默认无 """ """ S.center(width[, fillchar]) -> string 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): """ 子序列个数 """ """ 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 decode(self, encoding=None, errors=None): """ 解码 """ """ S.decode([encoding[,errors]]) -> object Decodes S using the codec registered for encoding. encoding defaults to the default encoding. errors may be given to set a different error handling scheme. Default is 'strict' meaning that encoding errors raise a UnicodeDecodeError. Other possible values are 'ignore' and 'replace' as well as any other name registered with codecs.register_error that is able to handle UnicodeDecodeErrors. """ return object() def encode(self, encoding=None, errors=None): """ 编码，针对unicode """ """ S.encode([encoding[,errors]]) -> object Encodes S using the codec registered for encoding. encoding defaults to the default encoding. 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 is able to handle UnicodeEncodeErrors. """ return object() def endswith(self, suffix, start=None, end=None): """ 是否以 xxx 结束 """ """ 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=None): """ 将tab转换成空格，默认一个tab转换成8个空格 """ """ S.expandtabs([tabsize]) -> string 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): """ 寻找子序列位置，如果没找到，返回 -1 """ """ 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(*args, **kwargs): # known special case of str.format """ 字符串格式化，动态参数，将函数式编程时细说 """ """ S.format(*args, **kwargs) -> string Return a formatted version of S, using substitutions from args and kwargs. The substitutions are identified by braces ('{' and '}'). """ pass def index(self, sub, start=None, end=None): """ 子序列位置，如果没找到，报错 """ S.index(sub [,start [,end]]) -> int Like S.find() but raise ValueError when the substring is not found. """ return 0 def isalnum(self): """ 是否是字母和数字 """ """ 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): """ 是否是字母 """ """ 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 isdigit(self): """ 是否是数字 """ """ 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 islower(self): """ 是否小写 """ """ 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 isspace(self): """ 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): """ S.istitle() -> bool Return True if S is a titlecased string and there is at least one character in S, i.e. uppercase characters may only follow uncased characters and lowercase characters only cased ones. Return False otherwise. """ return False def isupper(self): """ 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): """ 连接 """ """ S.join(iterable) -> string 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): """ 内容左对齐，右侧填充 """ """ S.ljust(width[, fillchar]) -> string Return S left-justified in a string of length width. Padding is done using the specified fill character (default is a space). """ return "" def lower(self): """ 变小写 """ """ S.lower() -> string Return a copy of the string S converted to lowercase. """ return "" def lstrip(self, chars=None): """ 移除左侧空白 """ """ S.lstrip([chars]) -> string or unicode Return a copy of the string S with leading whitespace removed. If chars is given and not None, remove characters in chars instead. If chars is unicode, S will be converted to unicode before stripping """ return "" def partition(self, sep): """ 分割，前，中，后三部分 """ """ 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): """ 替换 """ """ S.replace(old, new[, count]) -> string Return a copy of string 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): """ 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): """ 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): """ S.rjust(width[, fillchar]) -> string 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): """ 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=None): """ S.rsplit([sep [,maxsplit]]) -> list of strings Return a list of the words in the string 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 or is None, any whitespace string is a separator. """ return [] def rstrip(self, chars=None): """ S.rstrip([chars]) -> string or unicode Return a copy of the string S with trailing whitespace removed. If chars is given and not None, remove characters in chars instead. If chars is unicode, S will be converted to unicode before stripping """ return "" def split(self, sep=None, maxsplit=None): """ 分割， maxsplit最多分割几次 """ """ S.split([sep [,maxsplit]]) -> list of strings Return a list of the words in the string 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=False): """ 根据换行分割 """ """ S.splitlines(keepends=False) -> 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): """ 是否起始 """ """ 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): """ 移除两段空白 """ """ S.strip([chars]) -> string or unicode 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. If chars is unicode, S will be converted to unicode before stripping """ return "" def swapcase(self): """ 大写变小写，小写变大写 """ """ S.swapcase() -> string Return a copy of the string S with uppercase characters converted to lowercase and vice versa. """ return "" def title(self): """ S.title() -> string Return a titlecased version of S, i.e. words start with uppercase characters, all remaining cased characters have lowercase. """ return "" def translate(self, table, deletechars=None): """ 转换，需要先做一个对应表，最后一个表示删除字符集合 intab = "aeiou" outtab = "12345" trantab = maketrans(intab, outtab) str = "this is string example....wow!!!" print str.translate(trantab, 'xm') """ """ S.translate(table [,deletechars]) -> string Return a copy of the string S, where all characters occurring in the optional argument deletechars are removed, and the remaining characters have been mapped through the given translation table, which must be a string of length 256 or None. If the table argument is None, no translation is applied and the operation simply removes the characters in deletechars. """ return "" def upper(self): """ S.upper() -> string Return a copy of the string S converted to uppercase. """ return "" def zfill(self, width): """方法返回指定长度的字符串，原字符串右对齐，前面填充0。""" """ S.zfill(width) -> string 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 _formatter_field_name_split(self, *args, **kwargs): # real signature unknown pass def _formatter_parser(self, *args, **kwargs): # real signature unknown pass def __add__(self, y): """ x.__add__(y) <==> x+y """ pass def __contains__(self, y): """ x.__contains__(y) <==> y in x """ pass def __eq__(self, y): """ x.__eq__(y) <==> x==y """ pass def __format__(self, format_spec): """ S.__format__(format_spec) -> string Return a formatted version of S as described by format_spec. """ return "" def __getattribute__(self, name): """ x.__getattribute__('name') <==> x.name """ pass def __getitem__(self, y): """ x.__getitem__(y) <==> x[y] """ pass def __getnewargs__(self, *args, **kwargs): # real signature unknown pass def __getslice__(self, i, j): """ x.__getslice__(i, j) <==> x[i:j] Use of negative indices is not supported. """ pass def __ge__(self, y): """ x.__ge__(y) <==> x>=y """ pass def __gt__(self, y): """ x.__gt__(y) <==> x>y """ pass def __hash__(self): """ x.__hash__() <==> hash(x) """ pass def __init__(self, string=''): # known special case of str.__init__ """ str(object='') -> string Return a nice string representation of the object. If the argument is a string, the return value is the same object. # (copied from class doc) """ pass def __len__(self): """ x.__len__() <==> len(x) """ pass def __le__(self, y): """ x.__le__(y) <==> x<=y """ pass def __lt__(self, y): """ x.__lt__(y) <==> x<y """ pass def __mod__(self, y): """ x.__mod__(y) <==> x%y """ pass def __mul__(self, n): """ x.__mul__(n) <==> x*n """ 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 __ne__(self, y): """ x.__ne__(y) <==> x!=y """ pass def __repr__(self): """ x.__repr__() <==> repr(x) """ pass def __rmod__(self, y): """ x.__rmod__(y) <==> y%x """ pass def __rmul__(self, n): """ x.__rmul__(n) <==> n*x """ pass def __sizeof__(self): """ S.__sizeof__() -> size of S in memory, in bytes """ pass def __str__(self): """ x.__str__() <==> str(x) """ pass
- str_name.join（可迭代数据）
str1 = 'alex' s = '-'.join(str1) print(s) #结果为a-l-e-x li1 = ['alex','eric','wu'] s = '-'.join(li1) print(s) #结果为alex-eric-wu dict1 = {'k1':'alex','k2':'eric'} s = '-'.join(dict1) print(s) #结果为k1-k2
- str_name.strip（） 去两边空格 和lstrip 去左边空格、rstrip 去右边空格
str1 = ' a lex eric ' x1 = str1.strip() x2 = str1.lstrip() x3 = str1.rstrip() print(x1,len(x1)) print(x2,len(x2)) print(x3,len(x3)) 结果为： a lex eric 11 a lex eric 14 a lex eric 13
- str_name.partition（sub） 以某个子串把前后两侧分开，而且匹配第一个 返回元组
- str_name.split（sub） 以某个子串分后，并提出这个子串，匹配所有的 返回列表
str1 = 'alexshaobingalexshaobingalex' x1 = str1.partition('shaobing') print(x1) #结果为('alex', 'shaobing', 'alexshaobingalex') x2 = str1.split('shaobing') print(x2) #结果为['alex', 'alex', 'alex']
- str_name.replace（） 替换
str1 = 'ericshaobingericshaobingeric' x1 = str1.replace('shaobing','**') print(x1) #结果为eric**eric**eric
- str_name.title（） 可以理解为对每个单词进行首字母大写处理
str1 = 'Alex' x1 = str1.istitle() print(x1) #结果为True str2 = 'alex' x2 = str2.istitle() print(x2) #结果为False x3 = str2.title() print(x3) #结果为Alex
- str_name.startswith（） 以什么开头 和endswith（） 以什么结尾
s = 'eric' result1 = s.startswith('e') print(result1) #结果为True result2 = s.endswith('c') print(result2) #结果为True result3 = s.endswith('a') print(result3) #结果为False
- str_name.find（） 找到子串并返回索引位置，找不到返回-1，而index（）就会报错
s1 = 'alex' x1 = s1.find('e') print(x1) #结果为2 x2 = s1.find('c') print(x2) #找不到返回-1
- str_name.upper（） 变大写
s1 = 'alex' result = s1.upper() print(result) #结果为ALEX
- str_name.is..类型 判断是不是什么类型，返回Ture或Fulse
s1 = '123' result1 = s1.isdigit() print(result1) #结果为True s2 = '245x' result2 = s2.isdigit() print(result2) #结果为False
- len() 统计字符个数
s1 = 'alexeric' x = len(s1) print(x) #结果为8
- 索引 str_name[num] 获取一个字符（语言程序给每个元素按从左往右，第一个为0开始，编排一个位置，这个位置我们就叫做索引位置）
str1 = 'alex' x1 = str1[2] print(x1) #结果为e
- 切片 str_name[start_num:end_num] 获取从start_name到end_name - 1项字符
str1 = 'jixjidngisdgnsjci' x1 = str1[:] #获取整个字符串 x2 = str1[1:6] print(x1) #结果为jixjidngisdgnsjci print(x2) #结果为ixjid
- for循环 字符串里的字符可以用来循环的
s = 'alex' for i in s: print(i) 结果为： a l e x
4.list（列表）
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) -- append object to end """ pass 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) -- 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) -- 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, cmp=None, key=None, reverse=False): # real signature unknown; restored from __doc__ """ L.sort(cmp=None, key=None, reverse=False) -- stable sort *IN PLACE*; cmp(x, y) -> -1, 0, 1 """ pass def __add__(self, y): # real signature unknown; restored from __doc__ """ x.__add__(y) <==> x+y """ pass def __contains__(self, y): # real signature unknown; restored from __doc__ """ x.__contains__(y) <==> y in x """ pass def __delitem__(self, y): # real signature unknown; restored from __doc__ """ x.__delitem__(y) <==> del x[y] """ pass def __delslice__(self, i, j): # real signature unknown; restored from __doc__ """ x.__delslice__(i, j) <==> del x[i:j] Use of negative indices is not supported. """ pass def __eq__(self, y): # real signature unknown; restored from __doc__ """ x.__eq__(y) <==> x==y """ pass def __getattribute__(self, name): # real signature unknown; restored from __doc__ """ x.__getattribute__('name') <==> x.name """ pass def __getitem__(self, y): # real signature unknown; restored from __doc__ """ x.__getitem__(y) <==> x[y] """ pass def __getslice__(self, i, j): # real signature unknown; restored from __doc__ """ x.__getslice__(i, j) <==> x[i:j] Use of negative indices is not supported. """ pass def __ge__(self, y): # real signature unknown; restored from __doc__ """ x.__ge__(y) <==> x>=y """ pass def __gt__(self, y): # real signature unknown; restored from __doc__ """ x.__gt__(y) <==> x>y """ pass def __iadd__(self, y): # real signature unknown; restored from __doc__ """ x.__iadd__(y) <==> x+=y """ pass def __imul__(self, y): # real signature unknown; restored from __doc__ """ x.__imul__(y) <==> x*=y """ 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): # real signature unknown; restored from __doc__ """ x.__iter__() <==> iter(x) """ pass def __len__(self): # real signature unknown; restored from __doc__ """ x.__len__() <==> len(x) """ pass def __le__(self, y): # real signature unknown; restored from __doc__ """ x.__le__(y) <==> x<=y """ pass def __lt__(self, y): # real signature unknown; restored from __doc__ """ x.__lt__(y) <==> x<y """ pass def __mul__(self, n): # real signature unknown; restored from __doc__ """ x.__mul__(n) <==> x*n """ pass @staticmethod # known case of __new__ def __new__(S, *more): # real signature unknown; restored from __doc__ """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ pass def __ne__(self, y): # real signature unknown; restored from __doc__ """ x.__ne__(y) <==> x!=y """ pass def __repr__(self): # real signature unknown; restored from __doc__ """ x.__repr__() <==> repr(x) """ pass def __reversed__(self): # real signature unknown; restored from __doc__ """ L.__reversed__() -- return a reverse iterator over the list """ pass def __rmul__(self, n): # real signature unknown; restored from __doc__ """ x.__rmul__(n) <==> n*x """ pass def __setitem__(self, i, y): # real signature unknown; restored from __doc__ """ x.__setitem__(i, y) <==> x[i]=y """ pass def __setslice__(self, i, j, y): # real signature unknown; restored from __doc__ """ x.__setslice__(i, j, y) <==> x[i:j]=y Use of negative indices is not supported. """ pass def __sizeof__(self): # real signature unknown; restored from __doc__ """ L.__sizeof__() -- size of L in memory, in bytes """ pass __hash__ = None list
-
列表属于序列型数据类型，所以可以通过索引和切片来访问 -
语法结构 list_name[index] 切片
li = [1,2,3,6,5,4] print(li[2]) #结果为3
-
当然也通过索引删除数据项 del list_name[index]
li = [1,2,3,6,5,4] del li[2] print(li) #结果为[1, 2, 6, 5, 4]，删除了3
-
列表的切片 语法结构：list_name[start：end：step] 切片的返回结果也为列表
li = [1,2,3,6,5,4]
print(li[2]) #结
-
切片删除del list_name[start；end] 删除start到end-1项
li = [1,2,3,4,5] print(li[2:4]) #结果为[3, 4] del li[1:3] print(li) #结果为[1, 4, 5]，删除2,3
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加法
li1 = [4,2,6,2,9,3,3] li2 = range(10,15) #range函数现在输出的不是列表 print(li2) #结果为range(10, 15) li2 = list(li2) #转换为列表，再做加法（python3里range不能和列表直接串接） li3 = li1 + li2 print(li3) #结果为[4, 2, 6, 2, 9, 3, 3, 10, 11, 12, 13, 14]
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乘法
lis1 = ['that','good','boy'] lis2 = lis1 * 3 print(lis2) #结果为['that', 'good', 'boy', 'that', 'good', 'boy', 'that', 'good', 'boy']
-
列表的in和not in运算判断列表是否包含某个值
lis1 = [2,6,8,9] if 2 not in lis1: #条件不成立，所以下面没有输出 print('yes 2 not in lis1') lis2 = ['that','good','boy'] if 'that' in lis2: print('yes that in lis1') #结果为yes that in lis1
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列表的遍历 for循环
li1 = [1,23,69,452] li2 = li1 * 2 i = 0 #标记项初始化 for val in li2: print('第%d项：'%(i),val) #格式化控制字 i +=1 结果为： 第0项： 1 第1项： 23 第2项： 69 第3项： 452 第4项： 1 第5项： 23 第6项： 69 第7项： 452
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语法[val_expr for val in list_name] val_expr是变量val的运算表达式，val用于存储for每次从list_name列表里取出的值，用每个val_expr的值作为构建新列表的元素项
li = [1,5,3,9] li1 = [x**3 for x in li] print(li1) #结果为[1, 125, 27, 729] li2 = [x for x in range(4)] print(li2) #结果为[0, 1, 2, 3] li3 = [li2 for x in range(4)] print(li3) #结果为[[0, 1, 2, 3], [0, 1, 2, 3], [0, 1, 2, 3], [0, 1, 2, 3]] li4 = [li2 for x in li] print(li4) #结果为[[0, 1, 2, 3], [0, 1, 2, 3], [0, 1, 2, 3], [0, 1, 2, 3]] li4 = [2 for x in range(4)] #当val_expr为常项时，按后面列表项数为重复次数 print(li4) #结果为[2, 2, 2, 2]
-
统计项数 len函数
li = list(range(1,9)) print(len(li)) #结果为8
-
count函数 统计元素项相同的一个有几个
li1 = ['you','are','beautiful','girl'] li1 = li1 * 2 print(li1) #结果为['you', 'are', 'beautiful', 'girl', 'you', 'are', 'beautiful', 'girl'] print(li1.count('beautiful')) #结果为2 del li1[2] #删除beautiful print(li1) #结果为['you', 'are', 'girl', 'you', 'are', 'beautiful', 'girl'] print(li1.count(li1[5])) #删除一个beautiful后统计beautiful，结果为1
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insert（index，元素） 指定位置插入
li1 = ['let','is','make','love','everywhere'] li1.insert(2,99) print(li1) #结果为['let', 'is', 99, 'make', 'love', 'everywhere']
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append 指定项添加
li1 = ['let','is','make','love','everywhere'] li2 = [] for val in li1: li2.append(val) print(li2) #结果为['let', 'is', 'make', 'love', 'everywhere'] li2.append('pai') print(li2) #结果为['let', 'is', 'make', 'love', 'everywhere', 'pai'] li2.append(list(range(8))) #以一个整体项添加到列表的末尾 print(li2) #结果为['let', 'is', 'make', 'love', 'everywhere', 'pai', [0, 1, 2, 3, 4, 5, 6, 7]]
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extend函数 扩展函数 扩展列表是拆成单项加入被扩展列表的末尾
li1 = list(range(5)) li2 = list(range(6,9)) li1.extend(li2) print(li1) #结果为[0, 1, 2, 3, 4, 6, 7, 8]
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remove 指定项删除函数，而且只会匹配第一个删除
list1 = ['That','is','life','beautiful'] list1 = list1 * 2 print(list1) #结果为['That', 'is', 'life', 'beautiful', 'That', 'is', 'life', 'beautiful'] list1.remove('is') print(list1) #结果为['That', 'life', 'beautiful', 'That', 'is', 'life', 'beautiful']
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pop 默认最后一项删除，也可指定位置删除，并且删除时有返回值，返回值为即将要删除的
list1 = ['That','is','life','beautiful'] * 2 list1.pop() print(list1) #结果为['That', 'is', 'life', 'beautiful', 'That', 'is', 'life'] return_val = list1.pop(2) print(return_val,list1) #结果为life ['That', 'is', 'beautiful', 'That', 'is', 'life']
-
list_name.reverse() 元素顺序反转
lis = ['alex',55,22,'eric','nice'] lis.reverse() #结果为['nice', 'eric', 22, 55, 'alex'] print(lis)
- list_name.sore() 从小到大排序
li = [25,3,89,24,2541,58,41] li.sort() print(li) #结果为[3, 24, 25, 41, 58, 89, 2541]
5.tuple（元组）
lass tuple(object): """ tuple() -> empty tuple tuple(iterable) -> tuple initialized from iterable's items If the argument is a tuple, the return value is the same object. """ def count(self, value): # real signature unknown; restored from __doc__ """ T.count(value) -> integer -- return number of occurrences of value """ return 0 def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__ """ T.index(value, [start, [stop]]) -> integer -- return first index of value. Raises ValueError if the value is not present. """ return 0 def __add__(self, y): # real signature unknown; restored from __doc__ """ x.__add__(y) <==> x+y """ pass def __contains__(self, y): # real signature unknown; restored from __doc__ """ x.__contains__(y) <==> y in x """ pass def __eq__(self, y): # real signature unknown; restored from __doc__ """ x.__eq__(y) <==> x==y """ pass def __getattribute__(self, name): # real signature unknown; restored from __doc__ """ x.__getattribute__('name') <==> x.name """ pass def __getitem__(self, y): # real signature unknown; restored from __doc__ """ x.__getitem__(y) <==> x[y] """ pass def __getnewargs__(self, *args, **kwargs): # real signature unknown pass def __getslice__(self, i, j): # real signature unknown; restored from __doc__ """ x.__getslice__(i, j) <==> x[i:j] Use of negative indices is not supported. """ pass def __ge__(self, y): # real signature unknown; restored from __doc__ """ x.__ge__(y) <==> x>=y """ pass def __gt__(self, y): # real signature unknown; restored from __doc__ """ x.__gt__(y) <==> x>y """ pass def __hash__(self): # real signature unknown; restored from __doc__ """ x.__hash__() <==> hash(x) """ pass def __init__(self, seq=()): # known special case of tuple.__init__ """ tuple() -> empty tuple tuple(iterable) -> tuple initialized from iterable's items If the argument is a tuple, the return value is the same object. # (copied from class doc) """ pass def __iter__(self): # real signature unknown; restored from __doc__ """ x.__iter__() <==> iter(x) """ pass def __len__(self): # real signature unknown; restored from __doc__ """ x.__len__() <==> len(x) """ pass def __le__(self, y): # real signature unknown; restored from __doc__ """ x.__le__(y) <==> x<=y """ pass def __lt__(self, y): # real signature unknown; restored from __doc__ """ x.__lt__(y) <==> x<y """ pass def __mul__(self, n): # real signature unknown; restored from __doc__ """ x.__mul__(n) <==> x*n """ pass @staticmethod # known case of __new__ def __new__(S, *more): # real signature unknown; restored from __doc__ """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ pass def __ne__(self, y): # real signature unknown; restored from __doc__ """ x.__ne__(y) <==> x!=y """ pass def __repr__(self): # real signature unknown; restored from __doc__ """ x.__repr__() <==> repr(x) """ pass def __rmul__(self, n): # real signature unknown; restored from __doc__ """ x.__rmul__(n) <==> n*x """ pass def __sizeof__(self): # real signature unknown; restored from __doc__ """ T.__sizeof__() -- size of T in memory, in bytes """ pass 复制代码
- tuple的值不可修改，只支持查（切片和索引），另外还有可循环元组里的元素，长度len统计，成员运算，由于这些方法和列表相同，我这里就不赘述了
- 创建单个元素的元组:tuple1 = (1,)
- 元组的儿子不能变，但是孙子可以变
t = (11,22,['alex',{'k1':'v1'}]) t[2].append('eric') print(t) #(11, 22, ['alex', {'k1': 'v1'}, 'eric']) del t[2][1] print(t) #(11, 22, ['alex', 'eric']) # del t[2] # print(t) #报错
6.dict（字典）
class dict(object): """ dict() -> new empty dictionary dict(mapping) -> new dictionary initialized from a mapping object's (key, value) pairs dict(iterable) -> new dictionary initialized as if via: d = {} for k, v in iterable: d[k] = v dict(**kwargs) -> new dictionary initialized with the name=value pairs in the keyword argument list. For example: dict(one=1, two=2) """ def clear(self): # real signature unknown; restored from __doc__ """ 清除内容 """ """ D.clear() -> None. Remove all items from D. """ pass def copy(self): # real signature unknown; restored from __doc__ """ 浅拷贝 """ """ D.copy() -> a shallow copy of D """ pass @staticmethod # known case def fromkeys(S, v=None): # real signature unknown; restored from __doc__ """ dict.fromkeys(S[,v]) -> New dict with keys from S and values equal to v. v defaults to None. """ pass def get(self, k, d=None): # real signature unknown; restored from __doc__ """ 根据key获取值，d是默认值 """ """ D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None. """ pass def has_key(self, k): # real signature unknown; restored from __doc__ """ 是否有key """ """ D.has_key(k) -> True if D has a key k, else False """ return False def items(self): # real signature unknown; restored from __doc__ """ 所有项的列表形式 """ """ D.items() -> list of D's (key, value) pairs, as 2-tuples """ return [] def iteritems(self): # real signature unknown; restored from __doc__ """ 项可迭代 """ """ D.iteritems() -> an iterator over the (key, value) items of D """ pass def iterkeys(self): # real signature unknown; restored from __doc__ """ key可迭代 """ """ D.iterkeys() -> an iterator over the keys of D """ pass def itervalues(self): # real signature unknown; restored from __doc__ """ value可迭代 """ """ D.itervalues() -> an iterator over the values of D """ pass def keys(self): # real signature unknown; restored from __doc__ """ 所有的key列表 """ """ D.keys() -> list of D's keys """ return [] def pop(self, k, d=None): # real signature unknown; restored from __doc__ """ 获取并在字典中移除 """ """ D.pop(k[,d]) -> v, remove specified key and return the corresponding value. If key is not found, d is returned if given, otherwise KeyError is raised """ pass def popitem(self): # real signature unknown; restored from __doc__ """ 获取并在字典中移除 """ """ D.popitem() -> (k, v), remove and return some (key, value) pair as a 2-tuple; but raise KeyError if D is empty. """ pass def setdefault(self, k, d=None): # real signature unknown; restored from __doc__ """ 如果key不存在，则创建，如果存在，则返回已存在的值且不修改 """ """ D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D """ pass def update(self, E=None, **F): # known special case of dict.update """ 更新 {'name':'alex', 'age': 18000} [('name','sbsbsb'),] """ """ D.update([E, ]**F) -> None. Update D from dict/iterable E and F. If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k in F: D[k] = F[k] """ pass def values(self): # real signature unknown; restored from __doc__ """ 所有的值 """ """ D.values() -> list of D's values """ return [] def viewitems(self): # real signature unknown; restored from __doc__ """ 所有项，只是将内容保存至view对象中 """ """ D.viewitems() -> a set-like object providing a view on D's items """ pass def viewkeys(self): # real signature unknown; restored from __doc__ """ D.viewkeys() -> a set-like object providing a view on D's keys """ pass def viewvalues(self): # real signature unknown; restored from __doc__ """ D.viewvalues() -> an object providing a view on D's values """ pass def __cmp__(self, y): # real signature unknown; restored from __doc__ """ x.__cmp__(y) <==> cmp(x,y) """ pass def __contains__(self, k): # real signature unknown; restored from __doc__ """ D.__contains__(k) -> True if D has a key k, else False """ return False def __delitem__(self, y): # real signature unknown; restored from __doc__ """ x.__delitem__(y) <==> del x[y] """ pass def __eq__(self, y): # real signature unknown; restored from __doc__ """ x.__eq__(y) <==> x==y """ pass def __getattribute__(self, name): # real signature unknown; restored from __doc__ """ x.__getattribute__('name') <==> x.name """ pass def __getitem__(self, y): # real signature unknown; restored from __doc__ """ x.__getitem__(y) <==> x[y] """ pass def __ge__(self, y): # real signature unknown; restored from __doc__ """ x.__ge__(y) <==> x>=y """ pass def __gt__(self, y): # real signature unknown; restored from __doc__ """ x.__gt__(y) <==> x>y """ pass def __init__(self, seq=None, **kwargs): # known special case of dict.__init__ """ dict() -> new empty dictionary dict(mapping) -> new dictionary initialized from a mapping object's (key, value) pairs dict(iterable) -> new dictionary initialized as if via: d = {} for k, v in iterable: d[k] = v dict(**kwargs) -> new dictionary initialized with the name=value pairs in the keyword argument list. For example: dict(one=1, two=2) # (copied from class doc) """ pass def __iter__(self): # real signature unknown; restored from __doc__ """ x.__iter__() <==> iter(x) """ pass def __len__(self): # real signature unknown; restored from __doc__ """ x.__len__() <==> len(x) """ pass def __le__(self, y): # real signature unknown; restored from __doc__ """ x.__le__(y) <==> x<=y """ pass def __lt__(self, y): # real signature unknown; restored from __doc__ """ x.__lt__(y) <==> x<y """ pass @staticmethod # known case of __new__ def __new__(S, *more): # real signature unknown; restored from __doc__ """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ pass def __ne__(self, y): # real signature unknown; restored from __doc__ """ x.__ne__(y) <==> x!=y """ pass def __repr__(self): # real signature unknown; restored from __doc__ """ x.__repr__() <==> repr(x) """ pass def __setitem__(self, i, y): # real signature unknown; restored from __doc__ """ x.__setitem__(i, y) <==> x[i]=y """ pass def __sizeof__(self): # real signature unknown; restored from __doc__ """ D.__sizeof__() -> size of D in memory, in bytes """ pass __hash__ = None 复制代码
- 每一项元素都为一个键值对
- for i in dict_name 默认循环字典的key
dict1 = {'k1':123,'k2':456}
for i in dict1:
print(i)
结果为：
k1
k2
- dict_name.keys（）所有的key键 values 所有的值 和 items 所有的键值对
dict1 = {'k1':123,'k2':456}
x = dict1.keys()
print(x) #结果为dict_keys(['k2', 'k1'])
for v in dict1.values():
print(v)
结果为：
456
123
for k,v in dict1.items():
print(k,v)
结果为：
k2 456
k1 123
- dict_name.get（） 根据key获取值，如果key不存在，则返回一个默认值None，索引对于不存在的键报错
dict1 = {'k1':123,'k2':456}
x = dict1.get('k1')
print(x) #结果为123
x1 = dict1.get('k3')
print(x1) #结果为None
# x2 = dict1['k3']
# print(x2) #报错
- 判断某个键是否在字典里
dict1 = {'k1':123,'k2':456}
ret = 'k1' in dict1.keys()
print(ret) #结果为True
ret2 = 'k3' in dict1.keys()
print(ret2) #结果为False
- dict_name.update（） 字典更新
dict1 = {'k1':123,'k2':456}
dict2 = {'k1':234,'k3':'hello'}
dict1.update(dict2)
print(dict1) #结果为{'k2': 456, 'k3': 'hello', 'k1': 234}
- del dict_name[‘key’] 字典key对应的键值对 dict_name.clear（） 清空字典
dic = {'k2': 456, 'k3': 'hello', 'k1': 234}
del dic['k2']
print(dic) #结果为{'k3': 'hello', 'k1': 234}
dic.clear()
print(dic) #结果为{}
- dict_name.fromkeys（） 说不清这玩意干啥的，直接看效果吧
dic = {'k2': 456, 'k3': 'hello', 'k1': 234}
n = dic.fromkeys(['k1','k2'],'alex')
print(n) #结果为{'k2': 'alex', 'k1': 'alex'}
n2 = dic.fromkeys(['k1','k2','k3'],[])
print(n2) #结果为{'k2': [], 'k3': [], 'k1': []}
n2['k1'].append('nice')
print(n2) #结果为{'k2': ['nice'], 'k3': ['nice'], 'k1': ['nice']}
- len函数可以测得字典的数据项个数
dic = {'k2': 456, 'k3': 'hello', 'k1': 234}
n = len(dic)
print(n) #结果为3
- 字典元素值得访问可以通过键获取其对应的值
- 字典元素值得修改也可以通过键修改其对应的值
dic = {'k2': 456, 'k3': 'hello', 'k1': 234}
value1 = dic['k3']
print(value1) #结果为hello
dic['k2'] = 'nice'
print(dic) #结果为{'k2': 'nice', 'k1': 234, 'k3': 'hello'}
- 字典元素项的添加，可以通过dict_name[新键] = 新值 的方式来添加
dic = {'k2': 456, 'k3': 'hello', 'k1': 234}
dic['k4'] = 'nice'
print(dic) #结果为{'k3': 'hello', 'k2': 456, 'k4': 'nice', 'k1': 234}
- enumerate(可迭代的) 自动加上为索引位置的key
li = ['跑车','美女','电脑'] for key,item in enumerate(li,1): print(key,item) inp = int(input('请输入商品序号：')) print(li[inp - 1]) 结果为： 1 跑车 2 美女 3 电脑 请输入商品序号：2 美女
7.bytes（字节）
- 字符转换成字节
name = '小刘' for i in name: print(i) bytes_list = bytes(i,encoding = 'utf-8') print(bytes_list) for b in bytes_list: print(b) print(bin(b)) 结果为： 小 b'\xe5\xb0\x8f' #输出列表时，默认十六进制 229 #十进制，输出单个字节时默认十进制 0b11100101 #bin（十进制） 转为二进制 176 0b10110000 143 0b10001111 刘 b'\xe5\x88\x98' 229 0b11100101 136 0b10001000 152 0b10011000
- 字节转换成字符串
a = '李璐' b1 = bytes(a,encoding='utf-8') print(b1) #b'\xe6\x9d\x8e\xe7\x92\x90' b2 = bytes(a,encoding='gbk') print(b2) #b'\xc0\xee\xe8\xb4' newal = str(b1,encoding='utf-8') print(newal) #李璐 newa2 = str(b2,encoding='gbk') print(newa2) #李璐
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笔者：拍省先生
