标签：arch gets nic before res stderr most lead tab
内容概要：
一、python2 or 3
二、字符串拼接
三、字符串
四、列表、元祖
五、字典
六、集合
七、练习
| 一、python2 or python3 |
目前大多使用python2.7，随着时间的推移，python3将会成为python爱好者的主流。
python2和3区别：
1.PRINT IS A FUNCTION
1 Old: print "The answer is", 2*2 New: print("The answer is", 2*2)
2 Old: print x, # Trailing comma suppresses newline New: print(x, end=" ") # Appends a space instead of a newline
3 Old: print # Prints a newline
4 New: print() # You must call the function!
5 Old: print >>sys.stderr, "fatal error" New: print("fatal error", file=sys.stderr)
6 Old: print (x, y) # prints repr((x, y))
7 New: print((x, y)) # Not the same as print(x, y)!
2.某些库名改变
例如:
| 2.x | 3.x |
| _winreg | winreg |
| copy_reg | copyreg |
| Queue | queue |
| SockerServer | sockerserver |
| repr | reprlib |
3.ALL IS UNICODE NOW
所有的字符编码变为unicode
| 二、字符串拼接 |
方法一：使用“+”（不推荐）
1 name="su" 2 msg="my name is "+name 3 print(msg) 4 输出： 5 my name is su
方法二：使用格式化字符串
%s:字符串
%d:整数
%f:浮点数
1 name="su" 2 age=25 3 job="IT" 4 msg="my name is %s age %d job %s"%(name,age,job) 5 print(msg) 6 输出： 7 my name is su age 25 job IT
方法三：使用format进行格式化输出（变量名替换）
1 name="su" 2 age=25 3 job="IT" 4 msg=‘‘‘my name is:{_name} 5 age is: {_age} 6 job is: {_job}‘‘‘.format(_name=name,_age=age,_job=job) 7 print(msg) 8 输出： 9 my name is:su 10 age is: 25 11 job is: IT
或者：（位置替换）
1 name="su" 2 age=25 3 job="IT" 4 msg=‘‘‘my name is:{0} 5 age is: {1} 6 job is: {2}‘‘‘.format(name,age,job) 7 print(msg) 8 输出： 9 my name is:su 10 age is: 25 11 job is: IT
总结：对比以上三种方法,使用+方式进行拼接字符串会开辟较多的内存空间，效率低，推荐使用第二种和第三种方法。
| 三、字符串 |
1.字符串常用操作
1 name = "my \tname is {name} and i am {year} old" 2 print(name.capitalize())#首字母大写 3 print(name.count("a")) 4 print(name.center(50,"-"))#不够50字符，“-”补全 5 print(name.endswith("ex"))#判断是否ex结尾 6 print(name.expandtabs(tabsize=30)) 7 print(name[name.find("name"):]) 8 name is {name} and i am {year} old 9 print(name.format(name=‘alex‘,year=23)) 10 print(name.format_map( {‘name‘:‘alex‘,‘year‘:12} )) 11 print(‘ab23‘.isalnum()) 12 print(‘abA‘.isalpha()) 13 print(‘1A‘.isdecimal()) 14 print(‘1A‘.isdigit()) #是否为数字 15 print(‘a 1A‘.isidentifier()) #判读是不是一个合法的标识符 16 print(‘33A‘.isnumeric()) 17 print(‘My Name Is ‘.istitle()) 18 print(‘My Name Is ‘.isprintable()) #tty file ,drive file 19 print(‘My Name Is ‘.isupper()) 20 print(‘+‘.join( [‘1‘,‘2‘,‘3‘]) ) 21 print( name.ljust(50,‘*‘) ) 22 print( name.rjust(50,‘-‘) ) 23 print( ‘Alex‘.lower() )#字符串变为小写字母 24 print( ‘Alex‘.upper() )#字符串变为大写字母 25 print( ‘\nAlex‘.lstrip() ) 26 print( ‘Alex\n‘.rstrip() ) 27 print( ‘ Alex\n‘.strip() ) 28 p = str.maketrans("abcdefli",‘123$@456‘) 29 print("alex li".translate(p) ) 30 31 print(‘alex li‘.replace(‘l‘,‘L‘,1)) 32 print(‘alex lil‘.rfind(‘l‘)) 33 print(‘1+2+3+4‘.split(‘\n‘))#变为列表 34 [‘1+2+3+4‘] 35 print(‘1+2\n+3+4‘.splitlines()) 36 print(‘Alex Li‘.swapcase()) 37 print(‘lex li‘.title()) 38 print(‘lex li‘.zfill(50))
字符串对方法如下：
1 class str(basestring): 2 """ 3 str(object=‘‘) -> string 4 5 Return a nice string representation of the object. 6 If the argument is a string, the return value is the same object. 7 """ 8 def capitalize(self): 9 """ 首字母变大写 """ 10 """ 11 S.capitalize() -> string 12 13 Return a copy of the string S with only its first character 14 capitalized. 15 """ 16 return "" 17 18 def center(self, width, fillchar=None): 19 """ 内容居中，width：总长度；fillchar：空白处填充内容，默认无 """ 20 """ 21 S.center(width[, fillchar]) -> string 22 23 Return S centered in a string of length width. Padding is 24 done using the specified fill character (default is a space) 25 """ 26 return "" 27 28 def count(self, sub, start=None, end=None): 29 """ 子序列个数 """ 30 """ 31 S.count(sub[, start[, end]]) -> int 32 33 Return the number of non-overlapping occurrences of substring sub in 34 string S[start:end]. Optional arguments start and end are interpreted 35 as in slice notation. 36 """ 37 return 0 38 39 def decode(self, encoding=None, errors=None): 40 """ 解码 """ 41 """ 42 S.decode([encoding[,errors]]) -> object 43 44 Decodes S using the codec registered for encoding. encoding defaults 45 to the default encoding. errors may be given to set a different error 46 handling scheme. Default is ‘strict‘ meaning that encoding errors raise 47 a UnicodeDecodeError. Other possible values are ‘ignore‘ and ‘replace‘ 48 as well as any other name registered with codecs.register_error that is 49 able to handle UnicodeDecodeErrors. 50 """ 51 return object() 52 53 def encode(self, encoding=None, errors=None): 54 """ 编码，针对unicode """ 55 """ 56 S.encode([encoding[,errors]]) -> object 57 58 Encodes S using the codec registered for encoding. encoding defaults 59 to the default encoding. errors may be given to set a different error 60 handling scheme. Default is ‘strict‘ meaning that encoding errors raise 61 a UnicodeEncodeError. Other possible values are ‘ignore‘, ‘replace‘ and 62 ‘xmlcharrefreplace‘ as well as any other name registered with 63 codecs.register_error that is able to handle UnicodeEncodeErrors. 64 """ 65 return object() 66 67 def endswith(self, suffix, start=None, end=None): 68 """ 是否以 xxx 结束 """ 69 """ 70 S.endswith(suffix[, start[, end]]) -> bool 71 72 Return True if S ends with the specified suffix, False otherwise. 73 With optional start, test S beginning at that position. 74 With optional end, stop comparing S at that position. 75 suffix can also be a tuple of strings to try. 76 """ 77 return False 78 79 def expandtabs(self, tabsize=None): 80 """ 将tab转换成空格，默认一个tab转换成8个空格 """ 81 """ 82 S.expandtabs([tabsize]) -> string 83 84 Return a copy of S where all tab characters are expanded using spaces. 85 If tabsize is not given, a tab size of 8 characters is assumed. 86 """ 87 return "" 88 89 def find(self, sub, start=None, end=None): 90 """ 寻找子序列位置，如果没找到，返回 -1 """ 91 """ 92 S.find(sub [,start [,end]]) -> int 93 94 Return the lowest index in S where substring sub is found, 95 such that sub is contained within S[start:end]. Optional 96 arguments start and end are interpreted as in slice notation. 97 98 Return -1 on failure. 99 """ 100 return 0 101 102 def format(*args, **kwargs): # known special case of str.format 103 """ 字符串格式化，动态参数，将函数式编程时细说 """ 104 """ 105 S.format(*args, **kwargs) -> string 106 107 Return a formatted version of S, using substitutions from args and kwargs. 108 The substitutions are identified by braces (‘{‘ and ‘}‘). 109 """ 110 pass 111 112 def index(self, sub, start=None, end=None): 113 """ 子序列位置，如果没找到，报错 """ 114 S.index(sub [,start [,end]]) -> int 115 116 Like S.find() but raise ValueError when the substring is not found. 117 """ 118 return 0 119 120 def isalnum(self): 121 """ 是否是字母和数字 """ 122 """ 123 S.isalnum() -> bool 124 125 Return True if all characters in S are alphanumeric 126 and there is at least one character in S, False otherwise. 127 """ 128 return False 129 130 def isalpha(self): 131 """ 是否是字母 """ 132 """ 133 S.isalpha() -> bool 134 135 Return True if all characters in S are alphabetic 136 and there is at least one character in S, False otherwise. 137 """ 138 return False 139 140 def isdigit(self): 141 """ 是否是数字 """ 142 """ 143 S.isdigit() -> bool 144 145 Return True if all characters in S are digits 146 and there is at least one character in S, False otherwise. 147 """ 148 return False 149 150 def islower(self): 151 """ 是否小写 """ 152 """ 153 S.islower() -> bool 154 155 Return True if all cased characters in S are lowercase and there is 156 at least one cased character in S, False otherwise. 157 """ 158 return False 159 160 def isspace(self): 161 """ 162 S.isspace() -> bool 163 164 Return True if all characters in S are whitespace 165 and there is at least one character in S, False otherwise. 166 """ 167 return False 168 169 def istitle(self): 170 """ 171 S.istitle() -> bool 172 173 Return True if S is a titlecased string and there is at least one 174 character in S, i.e. uppercase characters may only follow uncased 175 characters and lowercase characters only cased ones. Return False 176 otherwise. 177 """ 178 return False 179 180 def isupper(self): 181 """ 182 S.isupper() -> bool 183 184 Return True if all cased characters in S are uppercase and there is 185 at least one cased character in S, False otherwise. 186 """ 187 return False 188 189 def join(self, iterable): 190 """ 连接 """ 191 """ 192 S.join(iterable) -> string 193 194 Return a string which is the concatenation of the strings in the 195 iterable. The separator between elements is S. 196 """ 197 return "" 198 199 def ljust(self, width, fillchar=None): 200 """ 内容左对齐，右侧填充 """ 201 """ 202 S.ljust(width[, fillchar]) -> string 203 204 Return S left-justified in a string of length width. Padding is 205 done using the specified fill character (default is a space). 206 """ 207 return "" 208 209 def lower(self): 210 """ 变小写 """ 211 """ 212 S.lower() -> string 213 214 Return a copy of the string S converted to lowercase. 215 """ 216 return "" 217 218 def lstrip(self, chars=None): 219 """ 移除左侧空白 """ 220 """ 221 S.lstrip([chars]) -> string or unicode 222 223 Return a copy of the string S with leading whitespace removed. 224 If chars is given and not None, remove characters in chars instead. 225 If chars is unicode, S will be converted to unicode before stripping 226 """ 227 return "" 228 229 def partition(self, sep): 230 """ 分割，前，中，后三部分 """ 231 """ 232 S.partition(sep) -> (head, sep, tail) 233 234 Search for the separator sep in S, and return the part before it, 235 the separator itself, and the part after it. If the separator is not 236 found, return S and two empty strings. 237 """ 238 pass 239 240 def replace(self, old, new, count=None): 241 """ 替换 """ 242 """ 243 S.replace(old, new[, count]) -> string 244 245 Return a copy of string S with all occurrences of substring 246 old replaced by new. If the optional argument count is 247 given, only the first count occurrences are replaced. 248 """ 249 return "" 250 251 def rfind(self, sub, start=None, end=None): 252 """ 253 S.rfind(sub [,start [,end]]) -> int 254 255 Return the highest index in S where substring sub is found, 256 such that sub is contained within S[start:end]. Optional 257 arguments start and end are interpreted as in slice notation. 258 259 Return -1 on failure. 260 """ 261 return 0 262 263 def rindex(self, sub, start=None, end=None): 264 """ 265 S.rindex(sub [,start [,end]]) -> int 266 267 Like S.rfind() but raise ValueError when the substring is not found. 268 """ 269 return 0 270 271 def rjust(self, width, fillchar=None): 272 """ 273 S.rjust(width[, fillchar]) -> string 274 275 Return S right-justified in a string of length width. Padding is 276 done using the specified fill character (default is a space) 277 """ 278 return "" 279 280 def rpartition(self, sep): 281 """ 282 S.rpartition(sep) -> (head, sep, tail) 283 284 Search for the separator sep in S, starting at the end of S, and return 285 the part before it, the separator itself, and the part after it. If the 286 separator is not found, return two empty strings and S. 287 """ 288 pass 289 290 def rsplit(self, sep=None, maxsplit=None): 291 """ 292 S.rsplit([sep [,maxsplit]]) -> list of strings 293 294 Return a list of the words in the string S, using sep as the 295 delimiter string, starting at the end of the string and working 296 to the front. If maxsplit is given, at most maxsplit splits are 297 done. If sep is not specified or is None, any whitespace string 298 is a separator. 299 """ 300 return [] 301 302 def rstrip(self, chars=None): 303 """ 304 S.rstrip([chars]) -> string or unicode 305 306 Return a copy of the string S with trailing whitespace removed. 307 If chars is given and not None, remove characters in chars instead. 308 If chars is unicode, S will be converted to unicode before stripping 309 """ 310 return "" 311 312 def split(self, sep=None, maxsplit=None): 313 """ 分割， maxsplit最多分割几次 """ 314 """ 315 S.split([sep [,maxsplit]]) -> list of strings 316 317 Return a list of the words in the string S, using sep as the 318 delimiter string. If maxsplit is given, at most maxsplit 319 splits are done. If sep is not specified or is None, any 320 whitespace string is a separator and empty strings are removed 321 from the result. 322 """ 323 return [] 324 325 def splitlines(self, keepends=False): 326 """ 根据换行分割 """ 327 """ 328 S.splitlines(keepends=False) -> list of strings 329 330 Return a list of the lines in S, breaking at line boundaries. 331 Line breaks are not included in the resulting list unless keepends 332 is given and true. 333 """ 334 return [] 335 336 def startswith(self, prefix, start=None, end=None): 337 """ 是否起始 """ 338 """ 339 S.startswith(prefix[, start[, end]]) -> bool 340 341 Return True if S starts with the specified prefix, False otherwise. 342 With optional start, test S beginning at that position. 343 With optional end, stop comparing S at that position. 344 prefix can also be a tuple of strings to try. 345 """ 346 return False 347 348 def strip(self, chars=None): 349 """ 移除两段空白 """ 350 """ 351 S.strip([chars]) -> string or unicode 352 353 Return a copy of the string S with leading and trailing 354 whitespace removed. 355 If chars is given and not None, remove characters in chars instead. 356 If chars is unicode, S will be converted to unicode before stripping 357 """ 358 return "" 359 360 def swapcase(self): 361 """ 大写变小写，小写变大写 """ 362 """ 363 S.swapcase() -> string 364 365 Return a copy of the string S with uppercase characters 366 converted to lowercase and vice versa. 367 """ 368 return "" 369 370 def title(self): 371 """ 372 S.title() -> string 373 374 Return a titlecased version of S, i.e. words start with uppercase 375 characters, all remaining cased characters have lowercase. 376 """ 377 return "" 378 379 def translate(self, table, deletechars=None): 380 """ 381 转换，需要先做一个对应表，最后一个表示删除字符集合 382 intab = "aeiou" 383 outtab = "12345" 384 trantab = maketrans(intab, outtab) 385 str = "this is string example....wow!!!" 386 print str.translate(trantab, ‘xm‘) 387 """ 388 389 """ 390 S.translate(table [,deletechars]) -> string 391 392 Return a copy of the string S, where all characters occurring 393 in the optional argument deletechars are removed, and the 394 remaining characters have been mapped through the given 395 translation table, which must be a string of length 256 or None. 396 If the table argument is None, no translation is applied and 397 the operation simply removes the characters in deletechars. 398 """ 399 return "" 400 401 def upper(self): 402 """ 403 S.upper() -> string 404 405 Return a copy of the string S converted to uppercase. 406 """ 407 return "" 408 409 def zfill(self, width): 410 """方法返回指定长度的字符串，原字符串右对齐，前面填充0。""" 411 """ 412 S.zfill(width) -> string 413 414 Pad a numeric string S with zeros on the left, to fill a field 415 of the specified width. The string S is never truncated. 416 """ 417 return "" 418 419 def _formatter_field_name_split(self, *args, **kwargs): # real signature unknown 420 pass 421 422 def _formatter_parser(self, *args, **kwargs): # real signature unknown 423 pass 424 425 def __add__(self, y): 426 """ x.__add__(y) <==> x+y """ 427 pass 428 429 def __contains__(self, y): 430 """ x.__contains__(y) <==> y in x """ 431 pass 432 433 def __eq__(self, y): 434 """ x.__eq__(y) <==> x==y """ 435 pass 436 437 def __format__(self, format_spec): 438 """ 439 S.__format__(format_spec) -> string 440 441 Return a formatted version of S as described by format_spec. 442 """ 443 return "" 444 445 def __getattribute__(self, name): 446 """ x.__getattribute__(‘name‘) <==> x.name """ 447 pass 448 449 def __getitem__(self, y): 450 """ x.__getitem__(y) <==> x[y] """ 451 pass 452 453 def __getnewargs__(self, *args, **kwargs): # real signature unknown 454 pass 455 456 def __getslice__(self, i, j): 457 """ 458 x.__getslice__(i, j) <==> x[i:j] 459 460 Use of negative indices is not supported. 461 """ 462 pass 463 464 def __ge__(self, y): 465 """ x.__ge__(y) <==> x>=y """ 466 pass 467 468 def __gt__(self, y): 469 """ x.__gt__(y) <==> x>y """ 470 pass 471 472 def __hash__(self): 473 """ x.__hash__() <==> hash(x) """ 474 pass 475 476 def __init__(self, string=‘‘): # known special case of str.__init__ 477 """ 478 str(object=‘‘) -> string 479 480 Return a nice string representation of the object. 481 If the argument is a string, the return value is the same object. 482 # (copied from class doc) 483 """ 484 pass 485 486 def __len__(self): 487 """ x.__len__() <==> len(x) """ 488 pass 489 490 def __le__(self, y): 491 """ x.__le__(y) <==> x<=y """ 492 pass 493 494 def __lt__(self, y): 495 """ x.__lt__(y) <==> x<y """ 496 pass 497 498 def __mod__(self, y): 499 """ x.__mod__(y) <==> x%y """ 500 pass 501 502 def __mul__(self, n): 503 """ x.__mul__(n) <==> x*n """ 504 pass 505 506 @staticmethod # known case of __new__ 507 def __new__(S, *more): 508 """ T.__new__(S, ...) -> a new object with type S, a subtype of T """ 509 pass 510 511 def __ne__(self, y): 512 """ x.__ne__(y) <==> x!=y """ 513 pass 514 515 def __repr__(self): 516 """ x.__repr__() <==> repr(x) """ 517 pass 518 519 def __rmod__(self, y): 520 """ x.__rmod__(y) <==> y%x """ 521 pass 522 523 def __rmul__(self, n): 524 """ x.__rmul__(n) <==> n*x """ 525 pass 526 527 def __sizeof__(self): 528 """ S.__sizeof__() -> size of S in memory, in bytes """ 529 pass 530 531 def __str__(self): 532 """ x.__str__() <==> str(x) """ 533 pass 534 535 str
| 四、列表、元祖 |
1.列表（list）
列表常用操作：
索引(index)
1 a=["a","b","c",1,2,3] 2 print(a.index("a"))#不加位置参数 3 输出： 4 0 5 a=["a","b","c","a",2,3] 6 print(a.index("b",1,5))#从索引1开始到5之间查找 7 输出： 8 1
切片(顾首不顾尾)
1 >>> names = ["Alex","Tenglan","Eric","Rain","Tom","Amy"] 2 >>> names[1:4] #取下标1至下标4之间的数字，包括1，不包括4 3 [‘Tenglan‘, ‘Eric‘, ‘Rain‘] 4 >>> names[1:-1] #取下标1至-1的值，不包括-1 5 [‘Tenglan‘, ‘Eric‘, ‘Rain‘, ‘Tom‘] 6 >>> names[0:3] 7 [‘Alex‘, ‘Tenglan‘, ‘Eric‘] 8 >>> names[:3] #如果是从头开始取，0可以忽略，跟上句效果一样 9 [‘Alex‘, ‘Tenglan‘, ‘Eric‘] 10 >>> names[3:] #如果想取最后一个，必须不能写-1，只能这么写 11 [‘Rain‘, ‘Tom‘, ‘Amy‘] 12 >>> names[3:-1] #这样-1就不会被包含了 13 [‘Rain‘, ‘Tom‘] 14 >>> names[-3:-1] #取最后两个效果同names[3:4] 15 [‘Tom‘,‘Amy‘] 16 >>> names[0::2] #后面的2是代表，每隔一个元素，就取一个 17 [‘Alex‘, ‘Eric‘, ‘Tom‘] 18 >>> names[::2] #和上句效果一样 19 [‘Alex‘, ‘Eric‘, ‘Tom‘]
追加(append)
1 a=["a","b","c","a",2,3] 2 a.append("SU") 3 print(a) 4 输出： 5 [‘a‘, ‘b‘, ‘c‘, ‘a‘, 2, 3, ‘SU‘]
删除(del，pop)
1 a=["a","b","c","d"] 2 del a[0] 3 print(a) 4 输出： 5 [‘b‘, ‘c‘, ‘d‘] 6 7 #pop 8 9 a=["a","b","c","d"] 10 a.pop() 11 print(a)#默认移除最后一个 12 输出： 13 [‘a‘, ‘b‘, ‘c‘] 14 #移除指定位置元素 15 a=["a","b","c","d"] 16 a.pop(2)#移除位置2的元素等价del a[2] 17 print(a) 18 输出： 19 [‘a‘, ‘b‘, ‘d‘]
插入(insert)
1 a=["a","b","c","a",2,3] 2 a.insert(0,"WD")#0代表索引，在0位置之前插入 3 print(a) 4 输出： 5 [‘WD‘, ‘a‘, ‘b‘, ‘c‘, ‘a‘, 2, 3]
扩展(extend)#列表的相加
1 a=["a","b","c"] 2 b=[1,2,3] 3 a.extend(b) 4 print(a) 5 输出： 6 [‘a‘, ‘b‘, ‘c‘, 1, 2, 3]
统计元素数量(count) 反序（reverse）
1 >>> names 2 [‘Alex‘, ‘Amy‘, ‘Amy‘, ‘Tenglan‘, ‘Tom‘, ‘1‘, ‘2‘, ‘3‘] 3 >>> names.sort() 4 >>> names 5 [‘1‘, ‘2‘, ‘3‘, ‘Alex‘, ‘Amy‘, ‘Amy‘, ‘Tenglan‘, ‘Tom‘] 6 7 >>> names.reverse() #反转 8 >>> names 9 [‘Tom‘, ‘Tenglan‘, ‘Amy‘, ‘Amy‘, ‘Alex‘, ‘3‘, ‘2‘, ‘1‘]
排序（sort）
1 >>> names 2 [‘Alex‘, ‘Tenglan‘, ‘Amy‘, ‘Tom‘, ‘Amy‘, 1, 2, 3] 3 >>> names.sort() #排序 4 Traceback (most recent call last): 5 File "<stdin>", line 1, in <module> 6 TypeError: unorderable types: int() < str() #3.0里不同数据类型不能放在一起排序了 7 >>> names[-3] = ‘1‘ 8 >>> names[-2] = ‘2‘ 9 >>> names[-1] = ‘3‘ 10 >>> names 11 [‘Alex‘, ‘Amy‘, ‘Amy‘, ‘Tenglan‘, ‘Tom‘, ‘1‘, ‘2‘, ‘3‘] 12 >>> names.sort() 13 >>> names 14 [‘1‘, ‘2‘, ‘3‘, ‘Alex‘, ‘Amy‘, ‘Amy‘, ‘Tenglan‘, ‘Tom‘] 15 16 >>> names.reverse() #反转 17 >>> names 18 [‘Tom‘, ‘Tenglan‘, ‘Amy‘, ‘Amy‘, ‘Alex‘, ‘3‘, ‘2‘, ‘1‘]
标签：arch gets nic before res stderr most lead tab
原文地址：http://www.cnblogs.com/xiangjun555/p/6800472.html
