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python之数据类型与变量
变量
变量作用：保存状态：说白了，程序运行的状态就是状态的变化，变量是用来保存状态的，变量值的不断变化就产生了运行程序的最终输出结果
一：声明变量
1 #!/usr/bin/env python 2 # -*- coding:utf-8 -*- 3 name=‘sy‘
上述代码声明了一个变量，变量名为： name，变量（name）的值为："sy"
二：变量的定义规则
- 变量名只能是 字母、数字或下划线的任意组合
- 变量名的第一个字符不能是数字（是字母或下划线(_)）
- 大小写敏感
- 两种风格：conn_obj或ConnObj
- 不能使用关键字，不能使用内建
以下关键字不能声明为变量名
[‘and‘, ‘as‘, ‘assert‘, ‘break‘, ‘class‘, ‘continue‘, ‘def‘, ‘del‘, ‘elif‘, ‘else‘, ‘except‘, ‘exec‘, ‘finally‘, ‘for‘, ‘from‘, ‘global‘, ‘if‘, ‘import‘, ‘in‘, ‘is‘, ‘lambda‘, ‘not‘, ‘or‘, ‘pass‘, ‘print‘, ‘raise‘, ‘return‘, ‘try‘, ‘while‘, ‘with‘, ‘yield‘]
三：变量赋值
链式赋值：y＝x＝z＝1
多元赋值：x,y=1,2 x,y=y,x
增量/减量/乘量/除量 赋值：
变量解压赋值：
数据类型
数据类型是在数据结构中的定义是一个值的集合以及定义在这个值集上的一组操作。
一、数据类型分类：
1、数字
int（整型）
python2.*与python3.*关于整型的区别
python2.*
在32位机器上，整数的位数为32位，取值范围为-2**31～2**31-1，即-2147483648～2147483647
在64位系统上，整数的位数为64位，取值范围为-2**63～2**63-1，即-9223372036854775808～9223372036854775807
1 class int(object): 2 """ 3 int(x=0) -> int or long 4 int(x, base=10) -> int or long 5 6 Convert a number or string to an integer, or return 0 if no arguments 7 are given. If x is floating point, the conversion truncates towards zero. 8 If x is outside the integer range, the function returns a long instead. 9 10 If x is not a number or if base is given, then x must be a string or 11 Unicode object representing an integer literal in the given base. The 12 literal can be preceded by ‘+‘ or ‘-‘ and be surrounded by whitespace. 13 The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to 14 interpret the base from the string as an integer literal. 15 >>> int(‘0b100‘, base=0) 16 """ 17 def bit_length(self): 18 """ 返回表示该数字的时占用的最少位数 """ 19 """ 20 int.bit_length() -> int 21 22 Number of bits necessary to represent self in binary. 23 >>> bin(37) 24 ‘0b100101‘ 25 >>> (37).bit_length() 26 """ 27 return 0 28 29 def conjugate(self, *args, **kwargs): # real signature unknown 30 """ 返回该复数的共轭复数 """ 31 """ Returns self, the complex conjugate of any int. """ 32 pass 33 34 def __abs__(self): 35 """ 返回绝对值 """ 36 """ x.__abs__() <==> abs(x) """ 37 pass 38 39 def __add__(self, y): 40 """ x.__add__(y) <==> x+y """ 41 pass 42 43 def __and__(self, y): 44 """ x.__and__(y) <==> x&y """ 45 pass 46 47 def __cmp__(self, y): 48 """ 比较两个数大小 """ 49 """ x.__cmp__(y) <==> cmp(x,y) """ 50 pass 51 52 def __coerce__(self, y): 53 """ 强制生成一个元组 """ 54 """ x.__coerce__(y) <==> coerce(x, y) """ 55 pass 56 57 def __divmod__(self, y): 58 """ 相除，得到商和余数组成的元组 """ 59 """ x.__divmod__(y) <==> divmod(x, y) """ 60 pass 61 62 def __div__(self, y): 63 """ x.__div__(y) <==> x/y """ 64 pass 65 66 def __float__(self): 67 """ 转换为浮点类型 """ 68 """ x.__float__() <==> float(x) """ 69 pass 70 71 def __floordiv__(self, y): 72 """ x.__floordiv__(y) <==> x//y """ 73 pass 74 75 def __format__(self, *args, **kwargs): # real signature unknown 76 pass 77 78 def __getattribute__(self, name): 79 """ x.__getattribute__(‘name‘) <==> x.name """ 80 pass 81 82 def __getnewargs__(self, *args, **kwargs): # real signature unknown 83 """ 内部调用 __new__方法或创建对象时传入参数使用 """ 84 pass 85 86 def __hash__(self): 87 """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。""" 88 """ x.__hash__() <==> hash(x) """ 89 pass 90 91 def __hex__(self): 92 """ 返回当前数的 十六进制 表示 """ 93 """ x.__hex__() <==> hex(x) """ 94 pass 95 96 def __index__(self): 97 """ 用于切片，数字无意义 """ 98 """ x[y:z] <==> x[y.__index__():z.__index__()] """ 99 pass 100 101 def __init__(self, x, base=10): # known special case of int.__init__ 102 """ 构造方法，执行 x = 123 或 x = int(10) 时，自动调用，暂时忽略 """ 103 """ 104 int(x=0) -> int or long 105 int(x, base=10) -> int or long 106 107 Convert a number or string to an integer, or return 0 if no arguments 108 are given. If x is floating point, the conversion truncates towards zero. 109 If x is outside the integer range, the function returns a long instead. 110 111 If x is not a number or if base is given, then x must be a string or 112 Unicode object representing an integer literal in the given base. The 113 literal can be preceded by ‘+‘ or ‘-‘ and be surrounded by whitespace. 114 The base defaults to 10. Valid bases are 0 and 2-36. Base 0 means to 115 interpret the base from the string as an integer literal. 116 >>> int(‘0b100‘, base=0) 117 # (copied from class doc) 118 """ 119 pass 120 121 def __int__(self): 122 """ 转换为整数 """ 123 """ x.__int__() <==> int(x) """ 124 pass 125 126 def __invert__(self): 127 """ x.__invert__() <==> ~x """ 128 pass 129 130 def __long__(self): 131 """ 转换为长整数 """ 132 """ x.__long__() <==> long(x) """ 133 pass 134 135 def __lshift__(self, y): 136 """ x.__lshift__(y) <==> x<<y """ 137 pass 138 139 def __mod__(self, y): 140 """ x.__mod__(y) <==> x%y """ 141 pass 142 143 def __mul__(self, y): 144 """ x.__mul__(y) <==> x*y """ 145 pass 146 147 def __neg__(self): 148 """ x.__neg__() <==> -x """ 149 pass 150 151 @staticmethod # known case of __new__ 152 def __new__(S, *more): 153 """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ 154 pass 155 156 def __nonzero__(self): 157 """ x.__nonzero__() <==> x != 0 """ 158 pass 159 160 def __oct__(self): 161 """ 返回改值的 八进制 表示 """ 162 """ x.__oct__() <==> oct(x) """ 163 pass 164 165 def __or__(self, y): 166 """ x.__or__(y) <==> x|y """ 167 pass 168 169 def __pos__(self): 170 """ x.__pos__() <==> +x """ 171 pass 172 173 def __pow__(self, y, z=None): 174 """ 幂，次方 """ 175 """ x.__pow__(y[, z]) <==> pow(x, y[, z]) """ 176 pass 177 178 def __radd__(self, y): 179 """ x.__radd__(y) <==> y+x """ 180 pass 181 182 def __rand__(self, y): 183 """ x.__rand__(y) <==> y&x """ 184 pass 185 186 def __rdivmod__(self, y): 187 """ x.__rdivmod__(y) <==> divmod(y, x) """ 188 pass 189 190 def __rdiv__(self, y): 191 """ x.__rdiv__(y) <==> y/x """ 192 pass 193 194 def __repr__(self): 195 """转化为解释器可读取的形式 """ 196 """ x.__repr__() <==> repr(x) """ 197 pass 198 199 def __str__(self): 200 """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""" 201 """ x.__str__() <==> str(x) """ 202 pass 203 204 def __rfloordiv__(self, y): 205 """ x.__rfloordiv__(y) <==> y//x """ 206 pass 207 208 def __rlshift__(self, y): 209 """ x.__rlshift__(y) <==> y<<x """ 210 pass 211 212 def __rmod__(self, y): 213 """ x.__rmod__(y) <==> y%x """ 214 pass 215 216 def __rmul__(self, y): 217 """ x.__rmul__(y) <==> y*x """ 218 pass 219 220 def __ror__(self, y): 221 """ x.__ror__(y) <==> y|x """ 222 pass 223 224 def __rpow__(self, x, z=None): 225 """ y.__rpow__(x[, z]) <==> pow(x, y[, z]) """ 226 pass 227 228 def __rrshift__(self, y): 229 """ x.__rrshift__(y) <==> y>>x """ 230 pass 231 232 def __rshift__(self, y): 233 """ x.__rshift__(y) <==> x>>y """ 234 pass 235 236 def __rsub__(self, y): 237 """ x.__rsub__(y) <==> y-x """ 238 pass 239 240 def __rtruediv__(self, y): 241 """ x.__rtruediv__(y) <==> y/x """ 242 pass 243 244 def __rxor__(self, y): 245 """ x.__rxor__(y) <==> y^x """ 246 pass 247 248 def __sub__(self, y): 249 """ x.__sub__(y) <==> x-y """ 250 pass 251 252 def __truediv__(self, y): 253 """ x.__truediv__(y) <==> x/y """ 254 pass 255 256 def __trunc__(self, *args, **kwargs): 257 """ 返回数值被截取为整形的值，在整形中无意义 """ 258 pass 259 260 def __xor__(self, y): 261 """ x.__xor__(y) <==> x^y """ 262 pass 263 264 denominator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 265 """ 分母 = 1 """ 266 """the denominator of a rational number in lowest terms""" 267 268 imag = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 269 """ 虚数，无意义 """ 270 """the imaginary part of a complex number""" 271 272 numerator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 273 """ 分子 = 数字大小 """ 274 """the numerator of a rational number in lowest terms""" 275 276 real = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 277 """ 实属，无意义 """ 278 """the real part of a complex number""" 279 280 int
python3.*整形长度无限制
1 class int(object): 2 """ 3 int(x=0) -> integer 4 int(x, base=10) -> integer 5 6 Convert a number or string to an integer, or return 0 if no arguments 7 are given. If x is a number, return x.__int__(). For floating point 8 numbers, this truncates towards zero. 9 10 If x is not a number or if base is given, then x must be a string, 11 bytes, or bytearray instance representing an integer literal in the 12 given base. The literal can be preceded by ‘+‘ or ‘-‘ and be surrounded 13 by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. 14 Base 0 means to interpret the base from the string as an integer literal. 15 >>> int(‘0b100‘, base=0) 16 """ 17 def bit_length(self): # real signature unknown; restored from __doc__ 18 """ 返回表示该数字的时占用的最少位数 """ 19 """ 20 int.bit_length() -> int 21 22 Number of bits necessary to represent self in binary. 23 >>> bin(37) 24 ‘0b100101‘ 25 >>> (37).bit_length() 26 """ 27 return 0 28 29 def conjugate(self, *args, **kwargs): # real signature unknown 30 """ 返回该复数的共轭复数 """ 31 """ Returns self, the complex conjugate of any int. """ 32 pass 33 34 @classmethod # known case 35 def from_bytes(cls, bytes, byteorder, *args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__ 36 """ 37 int.from_bytes(bytes, byteorder, *, signed=False) -> int 38 39 Return the integer represented by the given array of bytes. 40 41 The bytes argument must be a bytes-like object (e.g. bytes or bytearray). 42 43 The byteorder argument determines the byte order used to represent the 44 integer. If byteorder is ‘big‘, the most significant byte is at the 45 beginning of the byte array. If byteorder is ‘little‘, the most 46 significant byte is at the end of the byte array. To request the native 47 byte order of the host system, use `sys.byteorder‘ as the byte order value. 48 49 The signed keyword-only argument indicates whether two‘s complement is 50 used to represent the integer. 51 """ 52 pass 53 54 def to_bytes(self, length, byteorder, *args, **kwargs): # real signature unknown; NOTE: unreliably restored from __doc__ 55 """ 56 int.to_bytes(length, byteorder, *, signed=False) -> bytes 57 58 Return an array of bytes representing an integer. 59 60 The integer is represented using length bytes. An OverflowError is 61 raised if the integer is not representable with the given number of 62 bytes. 63 64 The byteorder argument determines the byte order used to represent the 65 integer. If byteorder is ‘big‘, the most significant byte is at the 66 beginning of the byte array. If byteorder is ‘little‘, the most 67 significant byte is at the end of the byte array. To request the native 68 byte order of the host system, use `sys.byteorder‘ as the byte order value. 69 70 The signed keyword-only argument determines whether two‘s complement is 71 used to represent the integer. If signed is False and a negative integer 72 is given, an OverflowError is raised. 73 """ 74 pass 75 76 def __abs__(self, *args, **kwargs): # real signature unknown 77 """ abs(self) """ 78 pass 79 80 def __add__(self, *args, **kwargs): # real signature unknown 81 """ Return self+value. """ 82 pass 83 84 def __and__(self, *args, **kwargs): # real signature unknown 85 """ Return self&value. """ 86 pass 87 88 def __bool__(self, *args, **kwargs): # real signature unknown 89 """ self != 0 """ 90 pass 91 92 def __ceil__(self, *args, **kwargs): # real signature unknown 93 """ 94 整数返回自己 95 如果是小数 96 math.ceil(3.1)返回4 97 """ 98 """ Ceiling of an Integral returns itself. """ 99 pass 100 101 def __divmod__(self, *args, **kwargs): # real signature unknown 102 """ 相除，得到商和余数组成的元组 """ 103 """ Return divmod(self, value). """ 104 pass 105 106 def __eq__(self, *args, **kwargs): # real signature unknown 107 """ Return self==value. """ 108 pass 109 110 def __float__(self, *args, **kwargs): # real signature unknown 111 """ float(self) """ 112 pass 113 114 def __floordiv__(self, *args, **kwargs): # real signature unknown 115 """ Return self//value. """ 116 pass 117 118 def __floor__(self, *args, **kwargs): # real signature unknown 119 """ Flooring an Integral returns itself. """ 120 pass 121 122 def __format__(self, *args, **kwargs): # real signature unknown 123 pass 124 125 def __getattribute__(self, *args, **kwargs): # real signature unknown 126 """ Return getattr(self, name). """ 127 pass 128 129 def __getnewargs__(self, *args, **kwargs): # real signature unknown 130 pass 131 132 def __ge__(self, *args, **kwargs): # real signature unknown 133 """ Return self>=value. """ 134 pass 135 136 def __gt__(self, *args, **kwargs): # real signature unknown 137 """ Return self>value. """ 138 pass 139 140 def __hash__(self, *args, **kwargs): # real signature unknown 141 """ Return hash(self). """ 142 pass 143 144 def __index__(self, *args, **kwargs): # real signature unknown 145 """ 用于切片，数字无意义 """ 146 """ Return self converted to an integer, if self is suitable for use as an index into a list. """ 147 pass 148 149 def __init__(self, x, base=10): # known special case of int.__init__ 150 """ 构造方法，执行 x = 123 或 x = int(10) 时，自动调用，暂时忽略 """ 151 """ 152 int(x=0) -> integer 153 int(x, base=10) -> integer 154 155 Convert a number or string to an integer, or return 0 if no arguments 156 are given. If x is a number, return x.__int__(). For floating point 157 numbers, this truncates towards zero. 158 159 If x is not a number or if base is given, then x must be a string, 160 bytes, or bytearray instance representing an integer literal in the 161 given base. The literal can be preceded by ‘+‘ or ‘-‘ and be surrounded 162 by whitespace. The base defaults to 10. Valid bases are 0 and 2-36. 163 Base 0 means to interpret the base from the string as an integer literal. 164 >>> int(‘0b100‘, base=0) 165 # (copied from class doc) 166 """ 167 pass 168 169 def __int__(self, *args, **kwargs): # real signature unknown 170 171 """ int(self) """ 172 pass 173 174 def __invert__(self, *args, **kwargs): # real signature unknown 175 """ ~self """ 176 pass 177 178 def __le__(self, *args, **kwargs): # real signature unknown 179 """ Return self<=value. """ 180 pass 181 182 def __lshift__(self, *args, **kwargs): # real signature unknown 183 """ Return self<<value. """ 184 pass 185 186 def __lt__(self, *args, **kwargs): # real signature unknown 187 """ Return self<value. """ 188 pass 189 190 def __mod__(self, *args, **kwargs): # real signature unknown 191 """ Return self%value. """ 192 pass 193 194 def __mul__(self, *args, **kwargs): # real signature unknown 195 """ Return self*value. """ 196 pass 197 198 def __neg__(self, *args, **kwargs): # real signature unknown 199 """ -self """ 200 pass 201 202 @staticmethod # known case of __new__ 203 def __new__(*args, **kwargs): # real signature unknown 204 """ Create and return a new object. See help(type) for accurate signature. """ 205 pass 206 207 def __ne__(self, *args, **kwargs): # real signature unknown 208 """ Return self!=value. """ 209 pass 210 211 def __or__(self, *args, **kwargs): # real signature unknown 212 """ Return self|value. """ 213 pass 214 215 def __pos__(self, *args, **kwargs): # real signature unknown 216 """ +self """ 217 pass 218 219 def __pow__(self, *args, **kwargs): # real signature unknown 220 """ Return pow(self, value, mod). """ 221 pass 222 223 def __radd__(self, *args, **kwargs): # real signature unknown 224 """ Return value+self. """ 225 pass 226 227 def __rand__(self, *args, **kwargs): # real signature unknown 228 """ Return value&self. """ 229 pass 230 231 def __rdivmod__(self, *args, **kwargs): # real signature unknown 232 """ Return divmod(value, self). """ 233 pass 234 235 def __repr__(self, *args, **kwargs): # real signature unknown 236 """ Return repr(self). """ 237 pass 238 239 def __rfloordiv__(self, *args, **kwargs): # real signature unknown 240 """ Return value//self. """ 241 pass 242 243 def __rlshift__(self, *args, **kwargs): # real signature unknown 244 """ Return value<<self. """ 245 pass 246 247 def __rmod__(self, *args, **kwargs): # real signature unknown 248 """ Return value%self. """ 249 pass 250 251 def __rmul__(self, *args, **kwargs): # real signature unknown 252 """ Return value*self. """ 253 pass 254 255 def __ror__(self, *args, **kwargs): # real signature unknown 256 """ Return value|self. """ 257 pass 258 259 def __round__(self, *args, **kwargs): # real signature unknown 260 """ 261 Rounding an Integral returns itself. 262 Rounding with an ndigits argument also returns an integer. 263 """ 264 pass 265 266 def __rpow__(self, *args, **kwargs): # real signature unknown 267 """ Return pow(value, self, mod). """ 268 pass 269 270 def __rrshift__(self, *args, **kwargs): # real signature unknown 271 """ Return value>>self. """ 272 pass 273 274 def __rshift__(self, *args, **kwargs): # real signature unknown 275 """ Return self>>value. """ 276 pass 277 278 def __rsub__(self, *args, **kwargs): # real signature unknown 279 """ Return value-self. """ 280 pass 281 282 def __rtruediv__(self, *args, **kwargs): # real signature unknown 283 """ Return value/self. """ 284 pass 285 286 def __rxor__(self, *args, **kwargs): # real signature unknown 287 """ Return value^self. """ 288 pass 289 290 def __sizeof__(self, *args, **kwargs): # real signature unknown 291 """ Returns size in memory, in bytes """ 292 pass 293 294 def __str__(self, *args, **kwargs): # real signature unknown 295 """ Return str(self). """ 296 pass 297 298 def __sub__(self, *args, **kwargs): # real signature unknown 299 """ Return self-value. """ 300 pass 301 302 def __truediv__(self, *args, **kwargs): # real signature unknown 303 """ Return self/value. """ 304 pass 305 306 def __trunc__(self, *args, **kwargs): # real signature unknown 307 """ Truncating an Integral returns itself. """ 308 pass 309 310 def __xor__(self, *args, **kwargs): # real signature unknown 311 """ Return self^value. """ 312 pass 313 314 denominator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 315 """the denominator of a rational number in lowest terms""" 316 317 imag = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 318 """the imaginary part of a complex number""" 319 320 numerator = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 321 """the numerator of a rational number in lowest terms""" 322 323 real = property(lambda self: object(), lambda self, v: None, lambda self: None) # default 324 """the real part of a complex number""" 325 326 python3.5
long（长整型）
python2.*：
跟C语言不同，Python的长整型没有指定位宽，也就是说Python没有限制长整型数值的大小，eg：
但是实际上由于机器内存有限，所以我们使用的长整型数值不可能无限大。
在使用过程中，我们如何区分长整型和整型数值呢？
通常的做法是在数字尾部加上一个大写字母L或小写字母l以表示该整数是长整型的，例如：
a = 9223372036854775808L
注意，自从Python2起，如果发生溢出，Python会自动将整型数据转换为长整型，
所以如今在长整型数据后面不加字母L也不会导致严重后果了。
python3.*
长整型，整型统一归为整型
float（浮点型）
浮点数也就是小数，之所以称为浮点数，是因为按照科学记数法表示时，一个浮点数的小数点位置是可变的，比如，1.23x109和12.3x108是完全相等的。浮点数可以用数学写法，如
1.23，3.14，-9.01，等等。但是对于很大或很小的浮点数，就必须用科学计数法表示，把10用e替代，1.23x109就是1.23e9，或者12.3e8，0.000012可以写成1.2e-5，等等。
整数和浮点数在计算机内部存储的方式是不同的，整数运算永远是精确的，而浮点数运算则可能会有四舍五入的误差
2、布尔值
真（True）或假（False）
0和空，None都是False，其他的全部为True
3：浮点数
浮点数也就是小数，之所以称为浮点数，是因为按照科学记数法表示时，一个浮点数的小数点位置是可变的，比如，1.23x109和12.3x108是完全相等的。浮点数可以用数学写法，如1.23，3.14，-9.01，等等。但是对于很大或很小的浮点数，就必须用科学计数法表示，把10用e替代，1.23x109就是1.23e9，或者12.3e8，0.000012可以写成1.2e-5，等等。
整数和浮点数在计算机内部存储的方式是不同的，整数运算永远是精确的，而浮点数运算则可能会有四舍五入的误差
4：复数
复数由实数部分和虚数部分组成，一般形式为x＋yj，其中的x是复数的实数部分，y是复数的虚数部分，这里的x和y都是实数。(虚数部分的字母j大小写都可以)
1 >>> 1.3 + 2.5j == 1.3 + 2.5J 2 True
5：与数字有关的内置函数
二：字符串
定义：
它是一个有序的字符的集合，用于存储和表示基本的文本信息，‘’或“”或‘’‘ ’‘’中间包含的内容称之为字符串
特性：
只能存放一个值
不可变
按照从左到右的顺序定义字符集合，下标从0开始顺序访问，有序
1：字符串创建
a=‘hello word‘
注：单引号和双引号没有任何区别
2：字符串的常用方法
1 name="yyp" 2 print(name.capitalize())#首字母变成大写 3 print(name.center(30)) # 居中 4 print(name.center(30,‘*‘))#居中加填充 5 6 msg=‘hello world‘ 7 print(msg.count(‘l‘))#统计出现l在msg中出现的次数 8 print(msg.count(‘l‘,0,3))#统计l在msg中0到3之间l出现的次数 9 print(msg.count(‘l‘,-1))#统计l在msg中最后一个字符中出现l的次数 10 print(msg.endswith(‘s‘))#判断msg是不是以s结尾，不是则为False，是为True 11 print(msg.startswith(‘h‘))#判断msg是不是以h开头，不是则为False，是为True 12 print(msg.find(‘l‘))#统计l出现的位置，如果不存在，则返回-1，存在返回位置，存在多个，只返回第一个出现的位置 13 print(msg.find(‘l‘,3,9))#统计l在msg的3到9之间，l出现的位置 14 print(msg.index(‘e‘))#index与find本质区别是：index已经知道msg中存在e，然后进行查找，如果不存在会报错。 15 print(msg.isdigit())#判断字符串中是否包含数字,包含数字为False，不包含为True 16 17 msg=‘hello world‘#多用于字符串拼接 18 msg_new=‘*‘.join(msg) 19 print(msg_new) 20 21 msg=‘root:x:0:0:root:/bin/bash‘ 22 print(msg.split(‘:‘)) #split分割 23 print(msg.split(‘:‘,maxsplit=1))#以：为分割符，最大分割一次 24 25 msg_list=msg.split(‘:‘) 26 print(‘:‘.join(msg_list))#按照：拼接字符串 27 28 msg=‘helLo world‘ 29 print(msg.upper())#小写转化为大写 30 print(msg.swapcase())#大小写转换 31 32 msg=‘*****yyp*****‘ 33 print(msg.strip(‘*‘))#去掉首尾的指定字符 34 print(msg.lstrip(‘*‘))#去除左边指定字符 35 print(msg.rstrip(‘*‘))#去除右边指定字符 36 37 38 print(msg.replace(‘z‘,‘y‘)) #替换字符，不指定个数全部替换，指定几个就替换几个 39 print(msg.replace(‘y‘,‘p‘,1))
3：字符串不常用的方法
1 #不常用的方法 2 msg=‘hello world‘ 3 print(msg.isalpha())#msg是纯字母返回True，不是则返回False 4 print(msg.isidentifier())#msg是内置标识符，返回True，否则返回False 5 print(msg.isspace())#msg是空格，返回True，反之，返回False 6 print(msg.istitle())#msg是标题，也就是首字母大写，返回True 7 print(msg.ljust(10))#10个字符左对齐 8 print(msg.ljust(10,‘*‘))#10个字符左对齐,10个字符*填充 9 print(msg.rjust(10))#10个字符右对齐 10 print(msg.rjust(10,‘*‘))#10个字符右对齐,10个字符*填充 11 print(msg.zfill(20))#总长度20个，不足则在右边添加0 12 13 message=‘‘‘aaa 14 bbb 15 ccc 16 ddd 17 ‘‘‘ 18 print(message.splitlines()) #按照行数切分
4:字符串工厂函数
1 class str(object): 2 """ 3 str(object=‘‘) -> str 4 str(bytes_or_buffer[, encoding[, errors]]) -> str 5 6 Create a new string object from the given object. If encoding or 7 errors is specified, then the object must expose a data buffer 8 that will be decoded using the given encoding and error handler. 9 Otherwise, returns the result of object.__str__() (if defined) 10 or repr(object). 11 encoding defaults to sys.getdefaultencoding(). 12 errors defaults to ‘strict‘. 13 """ 14 def capitalize(self): # real signature unknown; restored from __doc__ 15 """ 16 首字母变大写 17 S.capitalize() -> str 18 19 Return a capitalized version of S, i.e. make the first character 20 have upper case and the rest lower case. 21 """ 22 return "" 23 24 def casefold(self): # real signature unknown; restored from __doc__ 25 """ 26 S.casefold() -> str 27 28 Return a version of S suitable for caseless comparisons. 29 """ 30 return "" 31 32 def center(self, width, fillchar=None): # real signature unknown; restored from __doc__ 33 """ 34 原来字符居中，不够用空格补全 35 S.center(width[, fillchar]) -> str 36 37 Return S centered in a string of length width. Padding is 38 done using the specified fill character (default is a space) 39 """ 40 return "" 41 42 def count(self, sub, start=None, end=None): # real signature unknown; restored from __doc__ 43 """ 44 从一个范围内的统计某str出现次数 45 S.count(sub[, start[, end]]) -> int 46 47 Return the number of non-overlapping occurrences of substring sub in 48 string S[start:end]. Optional arguments start and end are 49 interpreted as in slice notation. 50 """ 51 return 0 52 53 def encode(self, encoding=‘utf-8‘, errors=‘strict‘): # real signature unknown; restored from __doc__ 54 """ 55 encode(encoding=‘utf-8‘,errors=‘strict‘) 56 以encoding指定编码格式编码，如果出错默认报一个ValueError，除非errors指定的是 57 ignore或replace 58 59 S.encode(encoding=‘utf-8‘, errors=‘strict‘) -> bytes 60 61 Encode S using the codec registered for encoding. Default encoding 62 is ‘utf-8‘. errors may be given to set a different error 63 handling scheme. Default is ‘strict‘ meaning that encoding errors raise 64 a UnicodeEncodeError. Other possible values are ‘ignore‘, ‘replace‘ and 65 ‘xmlcharrefreplace‘ as well as any other name registered with 66 codecs.register_error that can handle UnicodeEncodeErrors. 67 """ 68 return b"" 69 70 def endswith(self, suffix, start=None, end=None): # real signature unknown; restored from __doc__ 71 """ 72 S.endswith(suffix[, start[, end]]) -> bool 73 74 Return True if S ends with the specified suffix, False otherwise. 75 With optional start, test S beginning at that position. 76 With optional end, stop comparing S at that position. 77 suffix can also be a tuple of strings to try. 78 """ 79 return False 80 81 def expandtabs(self, tabsize=8): # real signature unknown; restored from __doc__ 82 """ 83 将字符串中包含的\t转换成tabsize个空格 84 S.expandtabs(tabsize=8) -> str 85 86 Return a copy of S where all tab characters are expanded using spaces. 87 If tabsize is not given, a tab size of 8 characters is assumed. 88 """ 89 return "" 90 91 def find(self, sub, start=None, end=None): # real signature unknown; restored from __doc__ 92 """ 93 S.find(sub[, start[, end]]) -> int 94 95 Return the lowest index in S where substring sub is found, 96 such that sub is contained within S[start:end]. Optional 97 arguments start and end are interpreted as in slice notation. 98 99 Return -1 on failure. 100 """ 101 return 0 102 103 def format(self, *args, **kwargs): # known special case of str.format 104 """ 105 格式化输出 106 三种形式： 107 形式一. 108 >>> print(‘{0}{1}{0}‘.format(‘a‘,‘b‘)) 109 aba 110 111 形式二：（必须一一对应） 112 >>> print(‘{}{}{}‘.format(‘a‘,‘b‘)) 113 Traceback (most recent call last): 114 File "<input>", line 1, in <module> 115 IndexError: tuple index out of range 116 >>> print(‘{}{}‘.format(‘a‘,‘b‘)) 117 ab 118 119 形式三： 120 >>> print(‘{name} {age}‘.format(age=12,name=‘lhf‘)) 121 lhf 12 122 123 S.format(*args, **kwargs) -> str 124 125 Return a formatted version of S, using substitutions from args and kwargs. 126 The substitutions are identified by braces (‘{‘ and ‘}‘). 127 """ 128 pass 129 130 def format_map(self, mapping): # real signature unknown; restored from __doc__ 131 """ 132 与format区别 133 ‘{name}‘.format(**dict(name=‘alex‘)) 134 ‘{name}‘.format_map(dict(name=‘alex‘)) 135 136 S.format_map(mapping) -> str 137 138 Return a formatted version of S, using substitutions from mapping. 139 The substitutions are identified by braces (‘{‘ and ‘}‘). 140 """ 141 return "" 142 143 def index(self, sub, start=None, end=None): # real signature unknown; restored from __doc__ 144 """ 145 S.index(sub[, start[, end]]) -> int 146 147 Like S.find() but raise ValueError when the substring is not found. 148 """ 149 return 0 150 151 def isalnum(self): # real signature unknown; restored from __doc__ 152 """ 153 至少一个字符，且都是字母或数字才返回True 154 155 S.isalnum() -> bool 156 157 Return True if all characters in S are alphanumeric 158 and there is at least one character in S, False otherwise. 159 """ 160 return False 161 162 def isalpha(self): # real signature unknown; restored from __doc__ 163 """ 164 至少一个字符，且都是字母才返回True 165 S.isalpha() -> bool 166 167 Return True if all characters in S are alphabetic 168 and there is at least one character in S, False otherwise. 169 """ 170 return False 171 172 def isdecimal(self): # real signature unknown; restored from __doc__ 173 """ 174 S.isdecimal() -> bool 175 176 Return True if there are only decimal characters in S, 177 False otherwise. 178 """ 179 return False 180 181 def isdigit(self): # real signature unknown; restored from __doc__ 182 """ 183 S.isdigit() -> bool 184 185 Return True if all characters in S are digits 186 and there is at least one character in S, False otherwise. 187 """ 188 return False 189 190 def isidentifier(self): # real signature unknown; restored from __doc__ 191 """ 192 字符串为关键字返回True 193 194 S.isidentifier() -> bool 195 196 Return True if S is a valid identifier according 197 to the language definition. 198 199 Use keyword.iskeyword() to test for reserved identifiers 200 such as "def" and "class". 201 """ 202 return False 203 204 def islower(self): # real signature unknown; restored from __doc__ 205 """ 206 至少一个字符，且都是小写字母才返回True 207 S.islower() -> bool 208 209 Return True if all cased characters in S are lowercase and there is 210 at least one cased character in S, False otherwise. 211 """ 212 return False 213 214 def isnumeric(self): # real signature unknown; restored from __doc__ 215 """ 216 S.isnumeric() -> bool 217 218 Return True if there are only numeric characters in S, 219 False otherwise. 220 """ 221 return False 222 223 def isprintable(self): # real signature unknown; restored from __doc__ 224 """ 225 S.isprintable() -> bool 226 227 Return True if all characters in S are considered 228 printable in repr() or S is empty, False otherwise. 229 """ 230 return False 231 232 def isspace(self): # real signature unknown; restored from __doc__ 233 """ 234 至少一个字符，且都是空格才返回True 235 S.isspace() -> bool 236 237 Return True if all characters in S are whitespace 238 and there is at least one character in S, False otherwise. 239 """ 240 return False 241 242 def istitle(self): # real signature unknown; restored from __doc__ 243 """ 244 >>> a=‘Hello‘ 245 >>> a.istitle() 246 True 247 >>> a=‘HellP‘ 248 >>> a.istitle() 249 False 250 251 S.istitle() -> bool 252 253 Return True if S is a titlecased string and there is at least one 254 character in S, i.e. upper- and titlecase characters may only 255 follow uncased characters and lowercase characters only cased ones. 256 Return False otherwise. 257 """ 258 return False 259 260 def isupper(self): # real signature unknown; restored from __doc__ 261 """ 262 S.isupper() -> bool 263 264 Return True if all cased characters in S are uppercase and there is 265 at least one cased character in S, False otherwise. 266 """ 267 return False 268 269 def join(self, iterable): # real signature unknown; restored from __doc__ 270 """ 271 #对序列进行操作（分别使用‘ ‘与‘:‘作为分隔符） 272 >>> seq1 = [‘hello‘,‘good‘,‘boy‘,‘doiido‘] 273 >>> print ‘ ‘.join(seq1) 274 hello good boy doiido 275 >>> print ‘:‘.join(seq1) 276 hello:good:boy:doiido 277 278 279 #对字符串进行操作 280 281 >>> seq2 = "hello good boy doiido" 282 >>> print ‘:‘.join(seq2) 283 h:e:l:l:o: :g:o:o:d: :b:o:y: :d:o:i:i:d:o 284 285 286 #对元组进行操作 287 288 >>> seq3 = (‘hello‘,‘good‘,‘boy‘,‘doiido‘) 289 >>> print ‘:‘.join(seq3) 290 hello:good:boy:doiido 291 292 293 #对字典进行操作 294 295 >>> seq4 = {‘hello‘:1,‘good‘:2,‘boy‘:3,‘doiido‘:4} 296 >>> print ‘:‘.join(seq4) 297 boy:good:doiido:hello 298 299 300 #合并目录 301 302 >>> import os 303 >>> os.path.join(‘/hello/‘,‘good/boy/‘,‘doiido‘) 304 ‘/hello/good/boy/doiido‘ 305 306 307 S.join(iterable) -> str 308 309 Return a string which is the concatenation of the strings in the 310 iterable. The separator between elements is S. 311 """ 312 return "" 313 314 def ljust(self, width, fillchar=None): # real signature unknown; restored from __doc__ 315 """ 316 S.ljust(width[, fillchar]) -> str 317 318 Return S left-justified in a Unicode string of length width. Padding is 319 done using the specified fill character (default is a space). 320 """ 321 return "" 322 323 def lower(self): # real signature unknown; restored from __doc__ 324 """ 325 S.lower() -> str 326 327 Return a copy of the string S converted to lowercase. 328 """ 329 return "" 330 331 def lstrip(self, chars=None): # real signature unknown; restored from __doc__ 332 """ 333 S.lstrip([chars]) -> str 334 335 Return a copy of the string S with leading whitespace removed. 336 If chars is given and not None, remove characters in chars instead. 337 """ 338 return "" 339 340 def maketrans(self, *args, **kwargs): # real signature unknown 341 """ 342 Return a translation table usable for str.translate(). 343 344 If there is only one argument, it must be a dictionary mapping Unicode 345 ordinals (integers) or characters to Unicode ordinals, strings or None. 346 Character keys will be then converted to ordinals. 347 If there are two arguments, they must be strings of equal length, and 348 in the resulting dictionary, each character in x will be mapped to the 349 character at the same position in y. If there is a third argument, it 350 must be a string, whose characters will be mapped to None in the result. 351 """ 352 pass 353 354 def partition(self, sep): # real signature unknown; restored from __doc__ 355 """ 356 以sep为分割，将S分成head,sep,tail三部分 357 358 S.partition(sep) -> (head, sep, tail) 359 360 Search for the separator sep in S, and return the part before it, 361 the separator itself, and the part after it. If the separator is not 362 found, return S and two empty strings. 363 """ 364 pass 365 366 def replace(self, old, new, count=None): # real signature unknown; restored from __doc__ 367 """ 368 S.replace(old, new[, count]) -> str 369 370 Return a copy of S with all occurrences of substring 371 old replaced by new. If the optional argument count is 372 given, only the first count occurrences are replaced. 373 """ 374 return "" 375 376 def rfind(self, sub, start=None, end=None): # real signature unknown; restored from __doc__ 377 """ 378 S.rfind(sub[, start[, end]]) -> int 379 380 Return the highest index in S where substring sub is found, 381 such that sub is contained within S[start:end]. Optional 382 arguments start and end are interpreted as in slice notation. 383 384 Return -1 on failure. 385 """ 386 return 0 387 388 def rindex(self, sub, start=None, end=None): # real signature unknown; restored from __doc__ 389 """ 390 S.rindex(sub[, start[, end]]) -> int 391 392 Like S.rfind() but raise ValueError when the substring is not found. 393 """ 394 return 0 395 396 def rjust(self, width, fillchar=None): # real signature unknown; restored from __doc__ 397 """ 398 S.rjust(width[, fillchar]) -> str 399 400 Return S right-justified in a string of length width. Padding is 401 done using the specified fill character (default is a space). 402 """ 403 return "" 404 405 def rpartition(self, sep): # real signature unknown; restored from __doc__ 406 """ 407 S.rpartition(sep) -> (head, sep, tail) 408 409 Search for the separator sep in S, starting at the end of S, and return 410 the part before it, the separator itself, and the part after it. If the 411 separator is not found, return two empty strings and S. 412 """ 413 pass 414 415 def rsplit(self, sep=None, maxsplit=-1): # real signature unknown; restored from __doc__ 416 """ 417 S.rsplit(sep=None, maxsplit=-1) -> list of strings 418 419 Return a list of the words in S, using sep as the 420 delimiter string, starting at the end of the string and 421 working to the front. If maxsplit is given, at most maxsplit 422 splits are done. If sep is not specified, any whitespace string 423 is a separator. 424 """ 425 return [] 426 427 def rstrip(self, chars=None): # real signature unknown; restored from __doc__ 428 """ 429 S.rstrip([chars]) -> str 430 431 Return a copy of the string S with trailing whitespace removed. 432 If chars is given and not None, remove characters in chars instead. 433 """ 434 return "" 435 436 def split(self, sep=None, maxsplit=-1): # real signature unknown; restored from __doc__ 437 """ 438 以sep为分割，将S切分成列表，与partition的区别在于切分结果不包含sep， 439 如果一个字符串中包含多个sep那么maxsplit为最多切分成几部分 440 >>> a=‘a,b c\nd\te‘ 441 >>> a.split() 442 [‘a,b‘, ‘c‘, ‘d‘, ‘e‘] 443 S.split(sep=None, maxsplit=-1) -> list of strings 444 445 Return a list of the words in S, using sep as the 446 delimiter string. If maxsplit is given, at most maxsplit 447 splits are done. If sep is not specified or is None, any 448 whitespace string is a separator and empty strings are 449 removed from the result. 450 """ 451 return [] 452 453 def splitlines(self, keepends=None): # real signature unknown; restored from __doc__ 454 """ 455 Python splitlines() 按照行(‘\r‘, ‘\r\n‘, \n‘)分隔， 456 返回一个包含各行作为元素的列表，如果参数 keepends 为 False，不包含换行符，如 果为 True，则保留换行符。 457 >>> x 458 ‘adsfasdf\nsadf\nasdf\nadf‘ 459 >>> x.splitlines() 460 [‘adsfasdf‘, ‘sadf‘, ‘asdf‘, ‘adf‘] 461 >>> x.splitlines(True) 462 [‘adsfasdf\n‘, ‘sadf\n‘, ‘asdf\n‘, ‘adf‘] 463 464 S.splitlines([keepends]) -> list of strings 465 466 Return a list of the lines in S, breaking at line boundaries. 467 Line breaks are not included in the resulting list unless keepends 468 is given and true. 469 """ 470 return [] 471 472 def startswith(self, prefix, start=None, end=None): # real signature unknown; restored from __doc__ 473 """ 474 S.startswith(prefix[, start[, end]]) -> bool 475 476 Return True if S starts with the specified prefix, False otherwise. 477 With optional start, test S beginning at that position. 478 With optional end, stop comparing S at that position. 479 prefix can also be a tuple of strings to try. 480 """ 481 return False 482 483 def strip(self, chars=None): # real signature unknown; restored from __doc__ 484 """ 485 S.strip([chars]) -> str 486 487 Return a copy of the string S with leading and trailing 488 whitespace removed. 489 If chars is given and not None, remove characters in chars instead. 490 """ 491 return "" 492 493 def swapcase(self): # real signature unknown; restored from __doc__ 494 """ 495 大小写反转 496 S.swapcase() -> str 497 498 Return a copy of S with uppercase characters converted to lowercase 499 and vice versa. 500 """ 501 return "" 502 503 def title(self): # real signature unknown; restored from __doc__ 504 """ 505 S.title() -> str 506 507 Return a titlecased version of S, i.e. words start with title case 508 characters, all remaining cased characters have lower case. 509 """ 510 return "" 511 512 def translate(self, table): # real signature unknown; restored from __doc__ 513 """ 514 table=str.maketrans(‘alex‘,‘big SB‘) 515 516 a=‘hello abc‘ 517 print(a.translate(table)) 518 519 S.translate(table) -> str 520 521 Return a copy of the string S in which each character has been mapped 522 through the given translation table. The table must implement 523 lookup/indexing via __getitem__, for instance a dictionary or list, 524 mapping Unicode ordinals to Unicode ordinals, strings, or None. If 525 this operation raises LookupError, the character is left untouched. 526 Characters mapped to None are deleted. 527 """ 528 return "" 529 530 def upper(self): # real signature unknown; restored from __doc__ 531 """ 532 S.upper() -> str 533 534 Return a copy of S converted to uppercase. 535 """ 536 return "" 537 538 def zfill(self, width): # real signature unknown; restored from __doc__ 539 """ 540 原来字符右对齐，不够用0补齐 541 542 S.zfill(width) -> str 543 544 Pad a numeric string S with zeros on the left, to fill a field 545 of the specified width. The string S is never truncated. 546 """ 547 return "" 548 549 def __add__(self, *args, **kwargs): # real signature unknown 550 """ Return self+value. """ 551 pass 552 553 def __contains__(self, *args, **kwargs): # real signature unknown 554 """ Return key in self. """ 555 pass 556 557 def __eq__(self, *args, **kwargs): # real signature unknown 558 """ Return self==value. """ 559 pass 560 561 def __format__(self, format_spec): # real signature unknown; restored from __doc__ 562 """ 563 S.__format__(format_spec) -> str 564 565 Return a formatted version of S as described by format_spec. 566 """ 567 return "" 568 569 def __getattribute__(self, *args, **kwargs): # real signature unknown 570 """ Return getattr(self, name). """ 571 pass 572 573 def __getitem__(self, *args, **kwargs): # real signature unknown 574 """ Return self[key]. """ 575 pass 576 577 def __getnewargs__(self, *args, **kwargs): # real signature unknown 578 pass 579 580 def __ge__(self, *args, **kwargs): # real signature unknown 581 """ Return self>=value. """ 582 pass 583 584 def __gt__(self, *args, **kwargs): # real signature unknown 585 """ Return self>value. """ 586 pass 587 588 def __hash__(self, *args, **kwargs): # real signature unknown 589 """ Return hash(self). """ 590 pass 591 592 def __init__(self, value=http://www.mamicode.com/‘‘, encoding=None, errors=‘strict‘): # known special case of str.__init__ 593 """ 594 str(object=‘‘) -> str 595 str(bytes_or_buffer[, encoding[, errors]]) -> str 596 597 Create a new string object from the given object. If encoding or 598 errors is specified, then the object must expose a data buffer 599 that will be decoded using the given encoding and error handler. 600 Otherwise, returns the result of object.__str__() (if defined) 601 or repr(object). 602 encoding defaults to sys.getdefaultencoding(). 603 errors defaults to ‘strict‘. 604 # (copied from class doc) 605 """ 606 pass 607 608 def __iter__(self, *args, **kwargs): # real signature unknown 609 """ Implement iter(self). """ 610 pass 611 612 def __len__(self, *args, **kwargs): # real signature unknown 613 """ Return len(self). """ 614 pass 615 616 def __le__(self, *args, **kwargs): # real signature unknown 617 """ Return self<=value. """ 618 pass 619 620 def __lt__(self, *args, **kwargs): # real signature unknown 621 """ Return self<value. """ 622 pass 623 624 def __mod__(self, *args, **kwargs): # real signature unknown 625 """ Return self%value. """ 626 pass 627 628 def __mul__(self, *args, **kwargs): # real signature unknown 629 """ Return self*value.n """ 630 pass 631 632 @staticmethod # known case of __new__ 633 def __new__(*args, **kwargs): # real signature unknown 634 """ Create and return a new object. See help(type) for accurate signature. """ 635 pass 636 637 def __ne__(self, *args, **kwargs): # real signature unknown 638 """ Return self!=value. """ 639 pass 640 641 def __repr__(self, *args, **kwargs): # real signature unknown 642 """ Return repr(self). """ 643 pass 644 645 def __rmod__(self, *args, **kwargs): # real signature unknown 646 """ Return value%self. """ 647 pass 648 649 def __rmul__(self, *args, **kwargs): # real signature unknown 650 """ Return self*value. """ 651 pass 652 653 def __sizeof__(self): # real signature unknown; restored from __doc__ 654 """ S.__sizeof__() -> size of S in memory, in bytes """ 655 pass 656 657 def __str__(self, *args, **kwargs): # real signature unknown 658 """ Return str(self). """ 659 pass
字符串索引，再看解压:
1 msg=‘hello‘ 2 #字符串索引操作 3 print(msg[4]) 4 print(msg[-2]) 5 #字符串的切分操作 6 print(msg[0:3]) #切分原则：顾头不顾尾 7 print(msg[0:]) 8 print(msg[:3]) 9 print(msg[0:2000:2])#按两个字符切分 10 print(msg[::-1])#hello倒过来 11 12 #再看变量解压操作 13 msg=‘hello‘ 14 x,y,z,*_=msg 15 print(x) 16 print(y) 17 print(z) 18 x,y,z=‘abc‘,‘aaa‘,‘xxx‘ 19 print(x) 20 print(y) 21 print(z)
三：列表
定义：
内以逗号分隔，按照索引，存放各种数据类型，每个位置代表一个元素
特性：
1.可存放多个值
2.可修改指定索引位置对应的值，可变
3.按照从左到右的顺序定义列表元素，下标从0开始顺序访问，有序
1：列表的创建
1 name_list=[‘yyp‘,‘sy‘,‘lxh‘,‘zmh‘]或name_list=list(‘yyp‘)或name=list([’yyp‘,‘sy‘])
列表常用方法
1 name_list=[‘yyp‘,‘sy‘,‘lxh‘,‘zmh‘] 2 #列表的索引操作 3 print(name_list[-1]) 4 print(name_list[0:2]) 5 print(name_list[::-1]) 6 #列表的内置方法 7 #append增加到末尾 8 name_list=[‘yyp‘,‘sy‘,‘lxh‘,‘zmh‘] 9 name_list.append(‘yy‘) 10 print(name_list) 11 #insert插入到指定位置 12 name_list=[‘yyp‘,‘sy‘,‘lxh‘,‘zmh‘] 13 name_list.insert(0,‘ylqh‘) 14 print(name_list) 15 #pop删除<br>name_list.pop()#默认从右边删除 16 name_list.pop(2)#指定删除第二个 17 print(name_list)<br> 18 #清空列表 19 name_list=[‘yyp‘,‘sy‘,‘lxh‘,‘zmh‘] 20 name_list.clear() 21 print(name_list) 22 23 #复制一份copy 24 name_list=[‘yyp‘,‘sy‘,‘lxh‘,‘zmh‘] 25 i=name_list.copy() 26 print(i) 27 28 #计数 29 name_list=[‘yyp‘,‘yy‘,‘sy‘,‘lxh‘,‘zmh‘,‘yy‘,‘zzl‘] 30 print(name_list.count(‘yy‘))#yy出现了几次 31 32 #两个列表合并 33 name_list=[‘yyp‘,‘sy‘,‘lxh‘,‘zmh‘] 34 nlist=[‘ylqi‘,‘lift‘] 35 name_list.extend(nlist) 36 print(name_list) 37 #单独加入列表 38 every_lis=‘xxx‘ 39 name_list.extend(every_lis) 40 print(name_list) 41 <br>#remove移除 42 name_list=[‘yyp‘,‘sy‘,‘lxh‘,‘zmh‘] 43 name_list.remove(lxhl‘)#按照元素名移除，有多个重复的元素值时，移除第一个 44 print(name_list) 45 46 #reverse反序排列<br>name_list=[‘yyp‘,‘sy‘,‘lxh‘,‘zmh‘] 47 name_list.reverse()#反序 48 print(name_list) 49 #sort排列 50 name_list=[‘d‘,‘c‘,‘A‘,‘1‘,‘@‘,‘*‘] 51 name_list.sort()#按照字符编码表排列 52 print(name_list) 53 #统计列表有几个元素或说成列表的长度 54 name_list=[‘yyp‘,‘sy‘,‘lxh‘,‘zmh‘] 55 print(len(name_list))#统计长度 56 57 #判断是否在列表里面 58 # name_list=[‘yyp‘,‘sy‘,‘lxh‘,‘zmh‘] 59 print (‘sy‘ in name_list) 60 print (‘l‘ in name_list)
3：列表工厂函数
1 class list(object): 2 """ 3 list() -> new empty list 4 list(iterable) -> new list initialized from iterable‘s items 5 """ 6 def append(self, p_object): # real signature unknown; restored from __doc__ 7 """ L.append(object) -> None -- append object to end """ 8 pass 9 10 def clear(self): # real signature unknown; restored from __doc__ 11 """ L.clear() -> None -- remove all items from L """ 12 pass 13 14 def copy(self): # real signature unknown; restored from __doc__ 15 """ L.copy() -> list -- a shallow copy of L """ 16 return [] 17 18 def count(self, value): # real signature unknown; restored from __doc__ 19 """ L.count(value) -> integer -- return number of occurrences of value """ 20 return 0 21 22 def extend(self, iterable): # real signature unknown; restored from __doc__ 23 """ L.extend(iterable) -> None -- extend list by appending elements from the iterable """ 24 pass 25 26 def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__ 27 """ 28 L.index(value, [start, [stop]]) -> integer -- return first index of value. 29 Raises ValueError if the value is not present. 30 """ 31 return 0 32 33 def insert(self, index, p_object): # real signature unknown; restored from __doc__ 34 """ L.insert(index, object) -- insert object before index """ 35 pass 36 37 def pop(self, index=None): # real signature unknown; restored from __doc__ 38 """ 39 L.pop([index]) -> item -- remove and return item at index (default last). 40 Raises IndexError if list is empty or index is out of range. 41 """ 42 pass 43 44 def remove(self, value): # real signature unknown; restored from __doc__ 45 """ 46 L.remove(value) -> None -- remove first occurrence of value. 47 Raises ValueError if the value is not present. 48 """ 49 pass 50 51 def reverse(self): # real signature unknown; restored from __doc__ 52 """ L.reverse() -- reverse *IN PLACE* """ 53 pass 54 55 def sort(self, key=None, reverse=False): # real signature unknown; restored from __doc__ 56 """ L.sort(key=None, reverse=False) -> None -- stable sort *IN PLACE* """ 57 pass 58 59 def __add__(self, *args, **kwargs): # real signature unknown 60 """ Return self+value. """ 61 pass 62 63 def __contains__(self, *args, **kwargs): # real signature unknown 64 """ Return key in self. """ 65 pass 66 67 def __delitem__(self, *args, **kwargs): # real signature unknown 68 """ Delete self[key]. """ 69 pass 70 71 def __eq__(self, *args, **kwargs): # real signature unknown 72 """ Return self==value. """ 73 pass 74 75 def __getattribute__(self, *args, **kwargs): # real signature unknown 76 """ Return getattr(self, name). """ 77 pass 78 79 def __getitem__(self, y): # real signature unknown; restored from __doc__ 80 """ x.__getitem__(y) <==> x[y] """ 81 pass 82 83 def __ge__(self, *args, **kwargs): # real signature unknown 84 """ Return self>=value. """ 85 pass 86 87 def __gt__(self, *args, **kwargs): # real signature unknown 88 """ Return self>value. """ 89 pass 90 91 def __iadd__(self, *args, **kwargs): # real signature unknown 92 """ Implement self+=value. """ 93 pass 94 95 def __imul__(self, *args, **kwargs): # real signature unknown 96 """ Implement self*=value. """ 97 pass 98 99 def __init__(self, seq=()): # known special case of list.__init__ 100 """ 101 list() -> new empty list 102 list(iterable) -> new list initialized from iterable‘s items 103 # (copied from class doc) 104 """ 105 pass 106 107 def __iter__(self, *args, **kwargs): # real signature unknown 108 """ Implement iter(self). """ 109 pass 110 111 def __len__(self, *args, **kwargs): # real signature unknown 112 """ Return len(self). """ 113 pass 114 115 def __le__(self, *args, **kwargs): # real signature unknown 116 """ Return self<=value. """ 117 pass 118 119 def __lt__(self, *args, **kwargs): # real signature unknown 120 """ Return self<value. """ 121 pass 122 123 def __mul__(self, *args, **kwargs): # real signature unknown 124 """ Return self*value.n """ 125 pass 126 127 @staticmethod # known case of __new__ 128 def __new__(*args, **kwargs): # real signature unknown 129 """ Create and return a new object. See help(type) for accurate signature. """ 130 pass 131 132 def __ne__(self, *args, **kwargs): # real signature unknown 133 """ Return self!=value. """ 134 pass 135 136 def __repr__(self, *args, **kwargs): # real signature unknown 137 """ Return repr(self). """ 138 pass 139 140 def __reversed__(self): # real signature unknown; restored from __doc__ 141 """ L.__reversed__() -- return a reverse iterator over the list """ 142 pass 143 144 def __rmul__(self, *args, **kwargs): # real signature unknown 145 """ Return self*value. """ 146 pass 147 148 def __setitem__(self, *args, **kwargs): # real signature unknown 149 """ Set self[key] to value. """ 150 pass 151 152 def __sizeof__(self): # real signature unknown; restored from __doc__ 153 """ L.__sizeof__() -- size of L in memory, in bytes """ 154 pass 155 156 __hash__ = None
四：元组
定义：
与列表差不多，只不过［］改成（），同时也叫作只读列表
特性：
1.可以存多个值
2.不可变
3.按照从左到右的顺序定义元组元素，下标从0开始顺序访问，有序
1：元组的创建
1 msg = (1,2,3,4,5) 2 ##或者 3 msg = tuple((1,2,3,4,5,6))
2：元组的常用方法
1 t=(‘yyp‘,‘sy‘,123) 2 print(t.count(‘sy‘))#统计sy的次数 3 print(t.index(‘sy‘))#统计sy的索引，没有则报错 4 print(len(t))#统计元组的长度 5 print(‘sy‘ in t) #包含，t是否包含sy
3：元组的工厂函数
1 lass tuple(object): 2 """ 3 tuple() -> empty tuple 4 tuple(iterable) -> tuple initialized from iterable‘s items 5 6 If the argument is a tuple, the return value is the same object. 7 """ 8 def count(self, value): # real signature unknown; restored from __doc__ 9 """ T.count(value) -> integer -- return number of occurrences of value """ 10 return 0 11 12 def index(self, value, start=None, stop=None): # real signature unknown; restored from __doc__ 13 """ 14 T.index(value, [start, [stop]]) -> integer -- return first index of value. 15 Raises ValueError if the value is not present. 16 """ 17 return 0 18 19 def __add__(self, y): # real signature unknown; restored from __doc__ 20 """ x.__add__(y) <==> x+y """ 21 pass 22 23 def __contains__(self, y): # real signature unknown; restored from __doc__ 24 """ x.__contains__(y) <==> y in x """ 25 pass 26 27 def __eq__(self, y): # real signature unknown; restored from __doc__ 28 """ x.__eq__(y) <==> x==y """ 29 pass 30 31 def __getattribute__(self, name): # real signature unknown; restored from __doc__ 32 """ x.__getattribute__(‘name‘) <==> x.name """ 33 pass 34 35 def __getitem__(self, y): # real signature unknown; restored from __doc__ 36 """ x.__getitem__(y) <==> x[y] """ 37 pass 38 39 def __getnewargs__(self, *args, **kwargs): # real signature unknown 40 pass 41 42 def __getslice__(self, i, j): # real signature unknown; restored from __doc__ 43 """ 44 x.__getslice__(i, j) <==> x[i:j] 45 46 Use of negative indices is not supported. 47 """ 48 pass 49 50 def __ge__(self, y): # real signature unknown; restored from __doc__ 51 """ x.__ge__(y) <==> x>=y """ 52 pass 53 54 def __gt__(self, y): # real signature unknown; restored from __doc__ 55 """ x.__gt__(y) <==> x>y """ 56 pass 57 58 def __hash__(self): # real signature unknown; restored from __doc__ 59 """ x.__hash__() <==> hash(x) """ 60 pass 61 62 def __init__(self, seq=()): # known special case of tuple.__init__ 63 """ 64 tuple() -> empty tuple 65 tuple(iterable) -> tuple initialized from iterable‘s items 66 67 If the argument is a tuple, the return value is the same object. 68 # (copied from class doc) 69 """ 70 pass 71 72 def __iter__(self): # real signature unknown; restored from __doc__ 73 """ x.__iter__() <==> iter(x) """ 74 pass 75 76 def __len__(self): # real signature unknown; restored from __doc__ 77 """ x.__len__() <==> len(x) """ 78 pass 79 80 def __le__(self, y): # real signature unknown; restored from __doc__ 81 """ x.__le__(y) <==> x<=y """ 82 pass 83 84 def __lt__(self, y): # real signature unknown; restored from __doc__ 85 """ x.__lt__(y) <==> x<y """ 86 pass 87 88 def __mul__(self, n): # real signature unknown; restored from __doc__ 89 """ x.__mul__(n) <==> x*n """ 90 pass 91 92 @staticmethod # known case of __new__ 93 def __new__(S, *more): # real signature unknown; restored from __doc__ 94 """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ 95 pass 96 97 def __ne__(self, y): # real signature unknown; restored from __doc__ 98 """ x.__ne__(y) <==> x!=y """ 99 pass 100 101 def __repr__(self): # real signature unknown; restored from __doc__ 102 """ x.__repr__() <==> repr(x) """ 103 pass 104 105 def __rmul__(self, n): # real signature unknown; restored from __doc__ 106 """ x.__rmul__(n) <==> n*x """ 107 pass 108 109 def __sizeof__(self): # real signature unknown; restored from __doc__ 110 """ T.__sizeof__() -- size of T in memory, in bytes """ 111 pass
4：元组的不可变行eg
1 t = (‘yyp‘, ‘sy‘, [‘YYP‘, ‘SY‘]) 2 print(t) 3 t[2][0] = ‘Y‘ 4 t[2][1] = ‘S‘ 5 print(t) 6 7 输出信息： 8 (‘yyp‘, ‘sy‘, [‘YYP‘, ‘SY‘]) 9 (‘yyp‘, ‘sy‘, [‘Y‘, ‘S‘])
五：字典
定义：
｛key:value｝,key-value 形式，key必须可hash
特性：
1.可存放多个值
2.可修改指定key对应的值，可变
3.无序
4.可变类型不能当做字典的key，value可以是任何数据类型
5.key不能重复
1：字典的创建
1 dic={‘name1‘:‘yyp‘,‘name2‘:‘sy‘} 2 或者 3 dic1={(1,2,3):‘aa‘} #元组可以当做key 4 或者 5 dic2 = dict(name=‘yyp‘, age=16) 6 或者 7 dic3 = dict({"name": "yyp", ‘age‘: 28}) 8 或者 9 dic4 = dict(([‘name‘,‘yyp‘],[‘age‘,120])) 10 11 输出结果： 12 {‘name1‘: ‘yyp‘, ‘name2‘: ‘sy‘} 13 {(1, 2, 3): ‘aa‘} 14 {‘name‘: ‘yyp‘, ‘age‘: 16} 15 {‘name‘: ‘yyp‘, ‘age‘: 28} 16 {‘name‘: ‘yyp‘, ‘age‘: 20}
2：字典的常用方法
1 取值： 2 info={‘msg1‘:‘yyp‘,‘msg2‘:‘sy‘,‘msg3‘:‘yp‘,‘msg4‘:‘yy‘} 3 print(‘msg1‘ in info) #标准用法,存在返回True，不存在返回False 4 print(info.get(‘msg2‘)) #获取 5 print(info[‘msg2‘]) #获取的到的时候，取值 6 7 print(info[‘msg8‘])#一旦获取不到，则报错 8 9 输出结果： 10 True 11 sy 12 sy 13 14 Traceback (most recent call last): 15 File "D:/my/python script/untitled/dict.py", line 21, in <module> 16 print(info[‘msg8‘])#一旦获取不到，则报错 17 KeyError: ‘msg8‘ 18 19 20 #增加 21 info={‘msg1‘:‘yyp‘,‘msg2‘:‘sy‘} 22 print(info) 23 info[‘msg3‘] = ‘yp‘#增加 24 print(info) 25 26 结果： 27 {‘msg1‘: ‘yyp‘, ‘msg2‘: ‘sy‘} 28 {‘msg1‘: ‘yyp‘, ‘msg2‘: ‘sy‘, ‘msg3‘: ‘yp‘} 29 30 31 #修改： 32 info={‘msg1‘:‘yyp‘,‘msg2‘:‘sy‘} 33 print(info) 34 info[‘msg2‘] = ‘yy‘ #修改 35 print(info) 36 37 结果： 38 {‘msg1‘: ‘yyp‘, ‘msg2‘: ‘sy‘} 39 {‘msg1‘: ‘yyp‘, ‘msg2‘: ‘yy‘} 40 41 42 一下五个都为删除用法： 43 info={‘msg1‘:‘yyp‘,‘msg2‘:‘sy‘,‘msg3‘:‘yp‘,‘msg4‘:‘yy‘} 44 print(info) 45 info.pop(‘msg3‘) 46 print(info) 47 del info[‘msg2‘] 48 print(info) 49 info.popitem()# 随机删除一个 50 print(info) 51 52 info.clear() #整个列表清空 53 print(info) 54 55 结果： 56 {‘msg1‘: ‘yyp‘, ‘msg2‘: ‘sy‘, ‘msg3‘: ‘yp‘, ‘msg4‘: ‘yy‘} 57 {‘msg1‘: ‘yyp‘, ‘msg2‘: ‘sy‘, ‘msg4‘: ‘yy‘} 58 {‘msg1‘: ‘yyp‘, ‘msg4‘: ‘yy‘} 59 {‘msg1‘: ‘yyp‘} 60 {}
3.字典的其他操作：
多级字典嵌套：
1 dict_name = { 2 "msg1":{ 3 "name1": ["于","one"], 4 "name2": ["孙","two"], 5 }, 6 "msg2":{ 7 "name3":["li","whree"] 8 }, 9 "msg3":{ 10 "name4":["张","four"] 11 } 12 } 13 14 dict_name["msg2"]["name3"][1] += ",你好" 15 print(dict_name["msg2"]["name3"]) 16 17 输出结果： 18 [‘li‘, ‘whree,你好‘]
4：字典的工厂函数
1 class dict(object): 2 """ 3 dict() -> new empty dictionary 4 dict(mapping) -> new dictionary initialized from a mapping object‘s 5 (key, value) pairs 6 dict(iterable) -> new dictionary initialized as if via: 7 d = {} 8 for k, v in iterable: 9 d[k] = v 10 dict(**kwargs) -> new dictionary initialized with the name=value pairs 11 in the keyword argument list. For example: dict(one=1, two=2) 12 """ 13 14 def clear(self): # real signature unknown; restored from __doc__ 15 """ 清除内容 """ 16 """ D.clear() -> None. Remove all items from D. """ 17 pass 18 19 def copy(self): # real signature unknown; restored from __doc__ 20 """ 浅拷贝 """ 21 """ D.copy() -> a shallow copy of D """ 22 pass 23 24 @staticmethod # known case 25 def fromkeys(S, v=None): # real signature unknown; restored from __doc__ 26 """ 27 dict.fromkeys(S[,v]) -> New dict with keys from S and values equal to v. 28 v defaults to None. 29 """ 30 pass 31 32 def get(self, k, d=None): # real signature unknown; restored from __doc__ 33 """ 根据key获取值，d是默认值 """ 34 """ D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None. """ 35 pass 36 37 def has_key(self, k): # real signature unknown; restored from __doc__ 38 """ 是否有key """ 39 """ D.has_key(k) -> True if D has a key k, else False """ 40 return False 41 42 def items(self): # real signature unknown; restored from __doc__ 43 """ 所有项的列表形式 """ 44 """ D.items() -> list of D‘s (key, value) pairs, as 2-tuples """ 45 return [] 46 47 def iteritems(self): # real signature unknown; restored from __doc__ 48 """ 项可迭代 """ 49 """ D.iteritems() -> an iterator over the (key, value) items of D """ 50 pass 51 52 def iterkeys(self): # real signature unknown; restored from __doc__ 53 """ key可迭代 """ 54 """ D.iterkeys() -> an iterator over the keys of D """ 55 pass 56 57 def itervalues(self): # real signature unknown; restored from __doc__ 58 """ value可迭代 """ 59 """ D.itervalues() -> an iterator over the values of D """ 60 pass 61 62 def keys(self): # real signature unknown; restored from __doc__ 63 """ 所有的key列表 """ 64 """ D.keys() -> list of D‘s keys """ 65 return [] 66 67 def pop(self, k, d=None): # real signature unknown; restored from __doc__ 68 """ 获取并在字典中移除 """ 69 """ 70 D.pop(k[,d]) -> v, remove specified key and return the corresponding value. 71 If key is not found, d is returned if given, otherwise KeyError is raised 72 """ 73 pass 74 75 def popitem(self): # real signature unknown; restored from __doc__ 76 """ 获取并在字典中移除 """ 77 """ 78 D.popitem() -> (k, v), remove and return some (key, value) pair as a 79 2-tuple; but raise KeyError if D is empty. 80 """ 81 pass 82 83 def setdefault(self, k, d=None): # real signature unknown; restored from __doc__ 84 """ 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 """ 85 """ D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D """ 86 pass 87 88 def update(self, E=None, **F): # known special case of dict.update 89 """ 更新 90 {‘name‘:‘alex‘, ‘age‘: 18000} 91 [(‘name‘,‘sbsbsb‘),] 92 """ 93 """ 94 D.update([E, ]**F) -> None. Update D from dict/iterable E and F. 95 If E present and has a .keys() method, does: for k in E: D[k] = E[k] 96 If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v 97 In either case, this is followed by: for k in F: D[k] = F[k] 98 """ 99 pass 100 101 def values(self): # real signature unknown; restored from __doc__ 102 """ 所有的值 """ 103 """ D.values() -> list of D‘s values """ 104 return [] 105 106 def viewitems(self): # real signature unknown; restored from __doc__ 107 """ 所有项，只是将内容保存至view对象中 """ 108 """ D.viewitems() -> a set-like object providing a view on D‘s items """ 109 pass 110 111 def viewkeys(self): # real signature unknown; restored from __doc__ 112 """ D.viewkeys() -> a set-like object providing a view on D‘s keys """ 113 pass 114 115 def viewvalues(self): # real signature unknown; restored from __doc__ 116 """ D.viewvalues() -> an object providing a view on D‘s values """ 117 pass 118 119 def __cmp__(self, y): # real signature unknown; restored from __doc__ 120 """ x.__cmp__(y) <==> cmp(x,y) """ 121 pass 122 123 def __contains__(self, k): # real signature unknown; restored from __doc__ 124 """ D.__contains__(k) -> True if D has a key k, else False """ 125 return False 126 127 def __delitem__(self, y): # real signature unknown; restored from __doc__ 128 """ x.__delitem__(y) <==> del x[y] """ 129 pass 130 131 def __eq__(self, y): # real signature unknown; restored from __doc__ 132 """ x.__eq__(y) <==> x==y """ 133 pass 134 135 def __getattribute__(self, name): # real signature unknown; restored from __doc__ 136 """ x.__getattribute__(‘name‘) <==> x.name """ 137 pass 138 139 def __getitem__(self, y): # real signature unknown; restored from __doc__ 140 """ x.__getitem__(y) <==> x[y] """ 141 pass 142 143 def __ge__(self, y): # real signature unknown; restored from __doc__ 144 """ x.__ge__(y) <==> x>=y """ 145 pass 146 147 def __gt__(self, y): # real signature unknown; restored from __doc__ 148 """ x.__gt__(y) <==> x>y """ 149 pass 150 151 def __init__(self, seq=None, **kwargs): # known special case of dict.__init__ 152 """ 153 dict() -> new empty dictionary 154 dict(mapping) -> new dictionary initialized from a mapping object‘s 155 (key, value) pairs 156 dict(iterable) -> new dictionary initialized as if via: 157 d = {} 158 for k, v in iterable: 159 d[k] = v 160 dict(**kwargs) -> new dictionary initialized with the name=value pairs 161 in the keyword argument list. For example: dict(one=1, two=2) 162 # (copied from class doc) 163 """ 164 pass 165 166 def __iter__(self): # real signature unknown; restored from __doc__ 167 """ x.__iter__() <==> iter(x) """ 168 pass 169 170 def __len__(self): # real signature unknown; restored from __doc__ 171 """ x.__len__() <==> len(x) """ 172 pass 173 174 def __le__(self, y): # real signature unknown; restored from __doc__ 175 """ x.__le__(y) <==> x<=y """ 176 pass 177 178 def __lt__(self, y): # real signature unknown; restored from __doc__ 179 """ x.__lt__(y) <==> x<y """ 180 pass 181 182 @staticmethod # known case of __new__ 183 def __new__(S, *more): # real signature unknown; restored from __doc__ 184 """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ 185 pass 186 187 def __ne__(self, y): # real signature unknown; restored from __doc__ 188 """ x.__ne__(y) <==> x!=y """ 189 pass 190 191 def __repr__(self): # real signature unknown; restored from __doc__ 192 """ x.__repr__() <==> repr(x) """ 193 pass 194 195 def __setitem__(self, i, y): # real signature unknown; restored from __doc__ 196 """ x.__setitem__(i, y) <==> x[i]=y """ 197 pass 198 199 def __sizeof__(self): # real signature unknown; restored from __doc__ 200 """ D.__sizeof__() -> size of D in memory, in bytes """ 201 pass 202 203 __hash__ = None
六、集合
1：集合的创建
1 msg = set([1,2,3])#创建一个数值的集合 2 print(msg) 3 或者 4 msg = set("hello")#创建一个唯一字符的集合 5 print(msg) 6 7 输出结果： 8 {1, 2, 3} 9 {‘h‘, ‘e‘, ‘o‘, ‘l‘}
2：集合的常用操作
1 msg = set([1, 1, 2, 2, 3, 3])#重复的元素自动过滤掉 2 print(msg) 3 4 结果： 5 {1, 2, 3} 6 7 msg.add(8) #可以添加元素到set中，可以重复添加，但是没有任何效果哦 8 print(msg) 9 10 结果： 11 {8, 1, 2, 3} 12 13 msg.remove(1)#删除set中的元素 14 print(msg) 15 16 结果： 17 {8, 2, 3} 18 19 msg.update([5,8,6])#在set中添加多项 20 print(msg) 21 22 结果： 23 {2, 3, 5, 6, 8} 24 25 print(len(msg))#set的长度 26 结果： 27 5
set关系运算
1 msg1 = set([2, 3, 5, 6, 8]) 2 msg2 = set([1,3,5]) 3 print(1 in msg1) #测试1是否是msg1的成员,是则返回True,否则返回False 4 5 输出结果： 6 False 7 8 print(1 not in msg1) #测试1是否不是msg1的成员，是则返回False，不是返回True 9 10 输出结果： 11 True 12 13 #测试是否msg2中的每一个元素都在msg1中 14 print(msg2.issubset(msg1)) 15 print(msg2 <= msg1) 16 17 输出结果： 18 False 19 False 20 21 #测试msg1中的每个元素都在msg2中 22 print(msg2.issuperset(msg1)) 23 print(msg2 >= msg1) 24 25 输出结果： 26 False 27 False 28 29 #返回一个新的set包含msg1和msg2的每一个元素 30 print(msg2.union(msg1)) 31 print(msg2 | msg1) 32 33 输出结果： 34 {1, 2, 3, 5, 6, 8} 35 {1, 2, 3, 5, 6, 8} 36 37 #返回一个新的set包含msg1与msg2的公共元素 38 print(msg2.intersection(msg1)) 39 print(msg1 & msg2) 40 41 输出结果： 42 {3, 5} 43 {3, 5} 44 45 #返回一个新的set包含msg2中有但是msg1中没有的元素 46 print(msg2.difference(msg1)) 47 print(msg2 - msg1) 48 49 输出结果： 50 {1} 51 {1} 52 53 #返回一个新的set包含msg2和msg1中不重复的元素 54 print(msg2.symmetric_difference(msg1)) 55 print(msg2 ^ msg1) 56 57 输出结果： 58 {1, 2, 6, 8} 59 {1, 2, 6, 8} 60 61 #返回set “msg1”的一个浅的复制 62 print(msg1.copy()) 63 64 输出结果： 65 {8, 2, 3, 5, 6}
set做交集、并集等操作
msg1 = set([1,3,5]) msg2 = set([1,2,3]) print(msg1 & msg2) #msg1与msg2的交集 print(msg1| msg2 ) #msg1与msg2的并集 print(msg1 - msg2) #求差集（元素在msg1中，但不在msg2中） print(msg1 ^ msg2) #对称差集（元素在msg1或msg2中，但不会同时出现在二者中） 输出结果： {1, 3} {1, 2, 3, 5} {5} {2, 5}
3：集合工厂
1 class set(object): 2 """ 3 set() -> new empty set object 4 set(iterable) -> new set object 5 6 Build an unordered collection of unique elements. 7 """ 8 def add(self, *args, **kwargs): # real signature unknown 9 """ 10 Add an element to a set. 11 12 This has no effect if the element is already present. 13 """ 14 pass 15 16 def clear(self, *args, **kwargs): # real signature unknown 17 """ Remove all elements from this set. """ 18 pass 19 20 def copy(self, *args, **kwargs): # real signature unknown 21 """ Return a shallow copy of a set. """ 22 pass 23 24 def difference(self, *args, **kwargs): # real signature unknown 25 """ 26 相当于s1-s2 27 28 Return the difference of two or more sets as a new set. 29 30 (i.e. all elements that are in this set but not the others.) 31 """ 32 pass 33 34 def difference_update(self, *args, **kwargs): # real signature unknown 35 """ Remove all elements of another set from this set. """ 36 pass 37 38 def discard(self, *args, **kwargs): # real signature unknown 39 """ 40 与remove功能相同，删除元素不存在时不会抛出异常 41 42 Remove an element from a set if it is a member. 43 44 If the element is not a member, do nothing. 45 """ 46 pass 47 48 def intersection(self, *args, **kwargs): # real signature unknown 49 """ 50 相当于s1&s2 51 52 Return the intersection of two sets as a new set. 53 54 (i.e. all elements that are in both sets.) 55 """ 56 pass 57 58 def intersection_update(self, *args, **kwargs): # real signature unknown 59 """ Update a set with the intersection of itself and another. """ 60 pass 61 62 def isdisjoint(self, *args, **kwargs): # real signature unknown 63 """ Return True if two sets have a null intersection. """ 64 pass 65 66 def issubset(self, *args, **kwargs): # real signature unknown 67 """ 68 相当于s1<=s2 69 70 Report whether another set contains this set. """ 71 pass 72 73 def issuperset(self, *args, **kwargs): # real signature unknown 74 """ 75 相当于s1>=s2 76 77 Report whether this set contains another set. """ 78 pass 79 80 def pop(self, *args, **kwargs): # real signature unknown 81 """ 82 Remove and return an arbitrary set element. 83 Raises KeyError if the set is empty. 84 """ 85 pass 86 87 def remove(self, *args, **kwargs): # real signature unknown 88 """ 89 Remove an element from a set; it must be a member. 90 91 If the element is not a member, raise a KeyError. 92 """ 93 pass 94 95 def symmetric_difference(self, *args, **kwargs): # real signature unknown 96 """ 97 相当于s1^s2 98 99 Return the symmetric difference of two sets as a new set. 100 101 (i.e. all elements that are in exactly one of the sets.) 102 """ 103 pass 104 105 def symmetric_difference_update(self, *args, **kwargs): # real signature unknown 106 """ Update a set with the symmetric difference of itself and another. """ 107 pass 108 109 def union(self, *args, **kwargs): # real signature unknown 110 """ 111 相当于s1|s2 112 113 Return the union of sets as a new set. 114 115 (i.e. all elements that are in either set.) 116 """ 117 pass 118 119 def update(self, *args, **kwargs): # real signature unknown 120 """ Update a set with the union of itself and others. """ 121 pass 122 123 def __and__(self, *args, **kwargs): # real signature unknown 124 """ Return self&value. """ 125 pass 126 127 def __contains__(self, y): # real signature unknown; restored from __doc__ 128 """ x.__contains__(y) <==> y in x. """ 129 pass 130 131 def __eq__(self, *args, **kwargs): # real signature unknown 132 """ Return self==value. """ 133 pass 134 135 def __getattribute__(self, *args, **kwargs): # real signature unknown 136 """ Return getattr(self, name). """ 137 pass 138 139 def __ge__(self, *args, **kwargs): # real signature unknown 140 """ Return self>=value. """ 141 pass 142 143 def __gt__(self, *args, **kwargs): # real signature unknown 144 """ Return self>value. """ 145 pass 146 147 def __iand__(self, *args, **kwargs): # real signature unknown 148 """ Return self&=value. """ 149 pass 150 151 def __init__(self, seq=()): # known special case of set.__init__ 152 """ 153 set() -> new empty set object 154 set(iterable) -> new set object 155 156 Build an unordered collection of unique elements. 157 # (copied from class doc) 158 """ 159 pass 160 161 def __ior__(self, *args, **kwargs): # real signature unknown 162 """ Return self|=value. """ 163 pass 164 165 def __isub__(self, *args, **kwargs): # real signature unknown 166 """ Return self-=value. """ 167 pass 168 169 def __iter__(self, *args, **kwargs): # real signature unknown 170 """ Implement iter(self). """ 171 pass 172 173 def __ixor__(self, *args, **kwargs): # real signature unknown 174 """ Return self^=value. """ 175 pass 176 177 def __len__(self, *args, **kwargs): # real signature unknown 178 """ Return len(self). """ 179 pass 180 181 def __le__(self, *args, **kwargs): # real signature unknown 182 """ Return self<=value. """ 183 pass 184 185 def __lt__(self, *args, **kwargs): # real signature unknown 186 """ Return self<value. """ 187 pass 188 189 @staticmethod # known case of __new__ 190 def __new__(*args, **kwargs): # real signature unknown 191 """ Create and return a new object. See help(type) for accurate signature. """ 192 pass 193 194 def __ne__(self, *args, **kwargs): # real signature unknown 195 """ Return self!=value. """ 196 pass 197 198 def __or__(self, *args, **kwargs): # real signature unknown 199 """ Return self|value. """ 200 pass 201 202 def __rand__(self, *args, **kwargs): # real signature unknown 203 """ Return value&self. """ 204 pass 205 206 def __reduce__(self, *args, **kwargs): # real signature unknown 207 """ Return state information for pickling. """ 208 pass 209 210 def __repr__(self, *args, **kwargs): # real signature unknown 211 """ Return repr(self). """ 212 pass 213 214 def __ror__(self, *args, **kwargs): # real signature unknown 215 """ Return value|self. """ 216 pass 217 218 def __rsub__(self, *args, **kwargs): # real signature unknown 219 """ Return value-self. """ 220 pass 221 222 def __rxor__(self, *args, **kwargs): # real signature unknown 223 """ Return value^self. """ 224 pass 225 226 def __sizeof__(self): # real signature unknown; restored from __doc__ 227 """ S.__sizeof__() -> size of S in memory, in bytes """ 228 pass 229 230 def __sub__(self, *args, **kwargs): # real signature unknown 231 """ Return self-value. """ 232 pass 233 234 def __xor__(self, *args, **kwargs): # real signature unknown 235 """ Return self^value. """ 236 pass 237 238 __hash__ = None
循环区别：
字符串循环:
1 #字符串循环： 2 方法1： 3 msg=‘love‘ 4 for i in msg: 5 print(i) 6 7 结果： 8 l 9 o 10 v 11 e 12 13 方法2： 14 for i in enumerate(msg): 15 print(i) 16 17 结果： 18 (0, ‘l‘) 19 (1, ‘o‘) 20 (2, ‘v‘) 21 (3, ‘e‘) 22 23 方法3：倒叙循环 24 for i in msg[::-1]: 25 print(i)
列表循环：
1 lis=[‘yyp‘,‘sy‘,‘yy‘] 2 for i in lis: 3 print(i) 4 5 for i in enumerate(lis): 6 print(i) 7 8 结果: 9 yyp 10 sy 11 yy 12 (0, ‘yyp‘) 13 (1, ‘sy‘) 14 (2, ‘yy‘)
元组循环：
1 tup=(‘x‘,‘y‘,‘z‘) 2 for i in tup: 3 print(i) 4 5 for i in enumerate(tup): 6 print(i) 7 8 结果： 9 x 10 y 11 z 12 (0, ‘x‘) 13 (1, ‘y‘) 14 (2, ‘z‘)
字典循环：
1 #字典循环 2 info={‘msg1‘:‘yyp‘,‘msg2‘:‘sy‘,‘msg3‘:‘zl‘,‘msg4‘:‘yy‘} 3 #方法1 4 for key in info: 5 print(key,info[key]) 6 7 结果 8 msg1 yyp 9 msg2 sy 10 msg3 zl 11 msg4 yy 12 13 #方法2 14 for k,v in info.items(): #会先把dict转成list,数据大时最好不要用 15 print(k,v) 16 17 结果： 18 msg1 yyp 19 msg2 sy 20 msg3 zl 21 msg4 yy 22 23 info={‘name1‘:‘yyp‘,‘name2‘:‘sy‘,‘name3‘:‘yy‘} 24 方法3： 25 info={‘name1‘:‘yyp‘,‘name2‘:‘sy‘,‘name3‘:‘yy‘} 26 for i in enumerate(info): 27 print(i) 28 29 结果： 30 (0, ‘name1‘) 31 (1, ‘name2‘) 32 (2, ‘name3‘) 33 34 方法4： 35 for i in info.keys(): 36 print(i,info[i]) 37 38 结果： 39 name1 yyp 40 name2 sy 41 name3 yy 42 43 方法5： 44 for v in info.values(): 45 print(v) 46 47 结果： 48 yyp 49 sy 50 yy
列表转为其他类型：
列表不可以转为字典
1 nums=[1,3,5,7,8,0] 2 3 #列表转为字符串： 4 print(str(nums),type(str(nums))) 5 6 结果： 7 [1, 3, 5, 7, 8, 0] <class ‘str‘> 8 9 #列表转为元组： 10 print(tuple(nums),type(tuple(nums))) 11 结果： 12 (1, 3, 5, 7, 8, 0) <class ‘tuple‘>
元组转为其他类型：
元组不可以转为字典
1 tup=(1, 2, 3, 4, 5) 2 3 #元组转为字符串 4 print(tup.__str__(),type(tup.__str__())) 5 6 结果： 7 (1, 2, 3, 4, 5) <class ‘str‘> 8 9 #元组转为列表 10 print(list(tup),type(list(tup))) 11 12 结果： 13 [1, 2, 3, 4, 5] <class ‘list‘>
字典转为其他类型：
1 dic = {‘name‘: ‘Zara‘, ‘age‘: 7, ‘class‘: ‘First‘} 2 3 #字典转为字符串 4 print(str(dic),type(str(dic))) 5 6 结果： 7 {‘age‘: 7, ‘name‘: ‘Zara‘, ‘class‘: ‘First‘} <class ‘str‘> 8 9 #字典可以转为元组 10 print(tuple(dic),type(tuple(dic))) 11 #字典可以转为元组 12 print(tuple(dic.values()),type(tuple(dic.values()))) 13 14 结果： 15 (‘age‘, ‘name‘, ‘class‘) <class ‘tuple‘> 16 (7, ‘Zara‘, ‘First‘) <class ‘tuple‘> 17 18 #字典转为列表 19 print(list(dic),type(list(dic))) 20 #字典转为列表 21 print(list(dic.values()),type(list(dic.values()))) 22 23 结果： 24 [‘age‘, ‘name‘, ‘class‘] <class ‘list‘> 25 [7, ‘Zara‘, ‘First‘] <class ‘list‘> 26 分类: python
总结
1.按存值个数区分
| 标量／原子类型 | 数字，字符串 |
| 容器类型 | 列表，元组，字典 |
2.按可变不可变区分
| 可变 | 列表，字典 |
| 不可变 | 数字，字符串，元组 |
证明：可变/不可变
更改数据类型其中的元素，如果内存地址发生变化，则为不可变类型，如果内存地址没有发生变化，则为可变类型。
详情参考：http://www.cnblogs.com/ylqh/p/6388330.html 的内存管理
3.按访问顺序区分
| 直接访问 | 数字 |
| 顺序访问（序列类型） | 字符串，列表，元组 |
| key值访问（映射类型） | 字典 |
补充：字典占用的内存空间比列表大，（因为要在内存空间保存一端时间的hash表）但是字典查询速度比列表快，联想到非关系型数据库比关系型数据查询要快应该就会想明白。
python之数据类型与变量
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