python123数值运算_python基础篇【第二篇】:数据运算、数据类型

一、数据运算

举个例子一目了然就明白什么是运算符了;例子10+20=30,其中10,20为操作符 ,“+” 称为运算符。

python支持支持的类型运算符有:算术运算、比较(关系)运算符、赋值运算符、逻辑运算符、位运算符、成员运算符、身份运算符、运算符优先级,下面我们一个个来看。

1、算数运算:

假设变量a=10,变量b=20:

运算符描述实例

+

加 – 两个对象相加

a + b 输出结果 30

减 – 得到负数或是一个数减去另一个数

a – b 输出结果 -10

*

乘 – 两个数相乘或是返回一个被重复若干次的字符串

a * b 输出结果 200

/

除 – x除以y

b / a 输出结果 2

%

取模 – 返回除法的余数

b % a 输出结果 0

**

幂 – 返回x的y次幂

a**b 为10的20次方, 输出结果 100000000000000000000

//

取整除 – 返回商的整数部分

9//2 输出结果 4 , 9.0//2.0 输出结果 4.0

练习实例:

1 #!/usr/bin/env python

2 #-*- coding :utf-8 -*-

3

4 a = 10

5 b = 20

6

7 c = a + b #两数相加

8 print(c)9

10 c = a – b #两数相减

11 print(c)12

13 c = a * b #两数相乘

14 print(c)15

16 c = a / b #两数相除

17 print(c)18

19 c = a % b #取模,返回除法的余数

20 print(c)21

22 c = a ** b #幂(次方)

23 print(c)24

25 c = a // b #取整数,返回商的整数部分

26 print(c)

以上练习实例执行结果

1 C:\Python\Python35\python.exe E:/Python课程/s13/day2/运算符.py2 30

3 -10

4 200

5 0.5

6 10

7 100000000000000000000

8 09

10 Process finished with exit code 0

2、比较运算符:

运算符描述实例

==

等于 – 比较对象是否相等

(a == b) 返回 False。

!=

不等于 – 比较两个对象是否不相等

(a != b) 返回 true.

<>

不等于 – 比较两个对象是否不相等(一般都用!=,在python3中已被移除)

(a <> b) 返回 true。这个运算符类似 != 。

>

大于 – 返回x是否大于y

(a > b) 返回 False。

<

小于 – 返回x是否小于y。所有比较运算符返回1表示真,返回0表示假。这分别与特殊的变量True和False等价。注意,这些变量名的大写。

(a < b) 返回 true。

>=

大于等于 – 返回x是否大于等于y。

(a >= b) 返回 False。

<=

小于等于 – 返回x是否小于等于y。

(a <= b) 返回 true。

实例练习:

1 a=66

2 b=88

3 c=04

5 a = 10

6 b = 20

78

9 if (a == b): #等于

10 print(‘a等于b’)11 else:12 print(‘a不等于b’)13

14 if (a != b): #不等于

15 print(‘a不等于b’)16 else:17 print(‘a等于b’)18

19 #if (a <> b): #不等于(python2.x)

20 #print(‘a不等于b’)

21 #else:

22 #print(‘a等于b’)

23

24

25 if (a < b): #小于

26 print(‘a小于b’)27 else:28 print(‘a不小于b’)29

30 if (a > b): #大于

31 print(‘a大于b’)32 else:33 print(‘a不大于b’)34

35

36 if (a <= b): #小于等于

37 print(‘a小于等于b’)38 else:39 print(‘不对’)40

41 if (a >= b): #大于等于

42 print(‘a大于等于b’)43 else:44 print(‘不对’)

以上实例执行结果:

C:\Python\Python35\python.exe E:/Python课程/s13/day2/运算符.py

错误

a不等于b

错误

a小于b

错误

a小于等于b

Process finished with exit code 0

3、赋值运算符:

运算符描述实例

=

简单的赋值运算符

c = a + b 将 a + b 的运算结果赋值为 c

+=

加法赋值运算符

c += a 等效于 c = c + a

-=

减法赋值运算符

c -= a 等效于 c = c – a

*=

乘法赋值运算符

c *= a 等效于 c = c * a

/=

除法赋值运算符

c /= a 等效于 c = c / a

%=

取模赋值运算符

c %= a 等效于 c = c % a

**=

幂赋值运算符

c **= a 等效于 c = c ** a

//=

取整除赋值运算符

c //= a 等效于 c = c // a

实例练习:

1 a = 2

2 b = 3

3 c =04

5 c = a + b #把a+b的变量和赋值给c变量

6 print(c)7

8 c += a #意思是c = c + a

9 print(c)10

11 c -= a #意思是c = c – a

12 print(c)13

14 c *= a #意思是c = c * a

15 print(c)16

17 c /= a #意思是c = c / a

18 print(c)19

20 c %= a #意思是c = c % a

21 print(c)22

23 c **= a #意思是c = c ** a

24 print(c)25

26 c //= a #意思是c = c // a

27 print(c)

以上实例执行结果:

1 C:\Python\Python35\python.exe E:/Python课程/s13/day2/运算符.py2 5

3 7

4 5

5 10

6 5.0

7 1.0

8 1.0

9 0.0

10

11 Process finished with exit code 0

4、位运算符:

执行二进制运算

运算符描述实例

&

按位与运算符:参与运算的两个值,如果两个相应位都为1,则该位的结果为1,否则为0

(a & b) 输出结果 12 ,二进制解释: 0000 1100

|

按位或运算符:只要对应的二个二进位有一个为1时,结果位就为1。

(a | b) 输出结果 61 ,二进制解释: 0011 1101

^

按位异或运算符:当两对应的二进位相异时,结果为1

(a ^ b) 输出结果 49 ,二进制解释: 0011 0001

~

按位取反运算符:对数据的每个二进制位取反,即把1变为0,把0变为1

(~a ) 输出结果 -61 ,二进制解释: 1100 0011, 在一个有符号二进制数的补码形式。

<<

左移动运算符:运算数的各二进位全部左移若干位,由”<<“右边的数指定移动的位数,高位丢弃,低位补0。

a << 2 输出结果 240 ,二进制解释: 1111 0000

>>

右移动运算符:把”>>”左边的运算数的各二进位全部右移若干位,”>>”右边的数指定移动的位数

a >> 2 输出结果 15 ,二进制解释: 0000 1111

实例练习:

#!/usr/bin/env python3

a= 10b= 60c=0#一下是数字转成二进制的方法#例如取10,60数字的二进制#128 64 32 16 8 4 2 1#0 0 0 0 1 0 1 0 = 10#0 0 1 1 1 1 0 0 = 60#0 0 0 0 1 0 0 0 = 8#

#所以数字10,60,的二进制分别为#10 = 1010#60 = 111100

c= a & b #按位与运算符:二进制位置中相对应的为1的则为1,否则为0

print(c)#128 64 32 16 8 4 2 1#0 0 0 0 1 0 1 0 = a = 10#0 0 1 1 1 1 0 0 = b = 60#0 0 0 0 1 0 0 0 = c = a & b = 8

c= a | b #按位或运算符:只要对应的位置是1的时候就是1

print(c)#128 64 32 16 8 4 2 1#0 0 0 0 1 0 1 0 = a = 10#0 0 1 1 1 1 0 0 = b = 60#0 0 1 1 1 1 1 0 = c = a | b = 62

c= a ^ b #按位异或运算符:就是相对应的位置不一样的时候等于1

print(c)#128 64 32 16 8 4 2 1#0 0 0 0 1 0 1 0 = a = 10#0 0 1 1 1 1 0 0 = b = 60#0 0 1 1 0 1 1 0 = c = a ^ b = 54

c= a << 2 #做移动运算符:往左边移动两位相当于 10*(2**2)左移n位就是乘以2的n次方

print(c)#128 64 32 16 8 4 2 1#0 0 0 0 1 0 1 0 = a = 10#0 0 1 0 1 0 0 0 = c = a << 2 = 40

c= a >> 2 #右移动运算符:往右边移动两位

print(c)#128 64 32 16 8 4 2 1#0 0 0 0 1 0 1 0 = a = 10#0 0 0 0 0 0 1 0 = c = a >>2 = 2

以上事例执行结果:

C:\Python\Python35\python.exe E:/Python课程/s13/day2/运算符.py8

62

54

40

2Process finished with exit code 0

5、逻辑运算符:

假设变量 a 为 10, b为 20:

运算符逻辑表达式描述实例

and

x and y

布尔”与” – 如果 x 为 False,x and y 返回 False,否则它返回 y 的计算值。

(a and b) 返回 20

or

x or y

布尔”或” – 如果 x 是 True,它返回 True,否则它返回 y 的计算值。

(a or b) 返回 10

not

not x

布尔”非” – 如果 x 为 True,返回 False 。如果 x 为 False,它返回 True。

not(a and b) 返回 False

6、成员运算符:

运算符描述实例

in

如果在指定的序列中找到值返回 True,否则返回 False。

x 在 y 序列中 , 如果 x 在 y 序列中返回 True。

not in

如果在指定的序列中没有找到值返回 True,否则返回 False。

x 不在 y 序列中 , 如果 x 不在 y 序列中返回 True。

二、数据类型:

1、数字数据类型

包含四种:

int整型 如:23、333

long长整型:就是比较大比较长的数字

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

大于以上范围着都属于长整型,只不过局限于python2中,在python3中已经不存在了!

float(浮点型):顾名思义就是带有小数点的数字,占8个字节(64位),其中52位表示底,11位表示指数,剩下的一位表示符号。

complex(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。

注:Python中存在小数字池:-5 ~ 257

其中使用的函数:

abs(x)

返回数字的绝对值,如abs(-10) 返回 10

2、布尔值

真或假(Ture、False)

1 或 0

3、字符串(str)

例如:”hello world” 这就是字符串,其中字符串有很多种用法如下:

ContractedBlock.gif

ExpandedBlockStart.gif

1 classstr(basestring):2 “””

3 str(object=”) -> string4

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 defcapitalize(self):9 “””首字母变大写”””

10 “””

11 S.capitalize() -> string12

13 Return a copy of the string S with only its first character14 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]) -> string22

23 Return S centered in a string of length width. Padding is24 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]]) -> int32

33 Return the number of non-overlapping occurrences of substring sub in34 string S[start:end]. Optional arguments start and end are interpreted35 as in slice notation.36 “””

37 return038

39 def decode(self, encoding=None, errors=None):40 “””解码”””

41 “””

42 S.decode([encoding[,errors]]) -> object43

44 Decodes S using the codec registered for encoding. encoding defaults45 to the default encoding. errors may be given to set a different error46 handling scheme. Default is ‘strict’ meaning that encoding errors raise47 a UnicodeDecodeError. Other possible values are ‘ignore’ and ‘replace’48 as well as any other name registered with codecs.register_error that is49 able to handle UnicodeDecodeErrors.50 “””

51 returnobject()52

53 def encode(self, encoding=None, errors=None):54 “””编码,针对unicode”””

55 “””

56 S.encode([encoding[,errors]]) -> object57

58 Encodes S using the codec registered for encoding. encoding defaults59 to the default encoding. errors may be given to set a different error60 handling scheme. Default is ‘strict’ meaning that encoding errors raise61 a UnicodeEncodeError. Other possible values are ‘ignore’, ‘replace’ and62 ‘xmlcharrefreplace’ as well as any other name registered with63 codecs.register_error that is able to handle UnicodeEncodeErrors.64 “””

65 returnobject()66

67 def endswith(self, suffix, start=None, end=None):68 “””是否以 xxx 结束”””

69 “””

70 S.endswith(suffix[, start[, end]]) -> bool71

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 returnFalse78

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]) -> string83

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]]) -> int93

94 Return the lowest index in S where substring sub is found,95 such that sub is contained within S[start:end]. Optional96 arguments start and end are interpreted as in slice notation.97

98 Return -1 on failure.99 “””

100 return0101

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) -> string106

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]]) ->int115

116 Like S.find() but raise ValueError when the substring is notfound.117 “””

118 return 0119

120 def isalnum(self):121 “”” 是否是字母和数字 “””

122 “””

123 S.isalnum() ->bool124

125 Return True if all characters inS are alphanumeric126 and there is at least one character inS, False otherwise.127 “””

128 return False129

130 def isalpha(self):131 “”” 是否是字母 “””

132 “””

133 S.isalpha() ->bool134

135 Return True if all characters inS are alphabetic136 and there is at least one character inS, False otherwise.137 “””

138 return False139

140 def isdigit(self):141 “”” 是否是数字 “””

142 “””

143 S.isdigit() ->bool144

145 Return True if all characters inS are digits146 and there is at least one character inS, False otherwise.147 “””

148 return False149

150 def islower(self):151 “”” 是否小写 “””

152 “””

153 S.islower() ->bool154

155 Return True if all cased characters in S are lowercase and there is

156 at least one cased character inS, False otherwise.157 “””

158 return False159

160 def isspace(self):161 “””

162 S.isspace() ->bool163

164 Return True if all characters inS are whitespace165 and there is at least one character inS, False otherwise.166 “””

167 return False168

169 def istitle(self):170 “””

171 S.istitle() ->bool172

173 Return True if S is a titlecased string and there isat least one174 character inS, i.e. uppercase characters may only follow uncased175 characters andlowercase characters only cased ones. Return False176 otherwise.177 “””

178 return False179

180 def isupper(self):181 “””

182 S.isupper() ->bool183

184 Return True if all cased characters in S are uppercase and there is

185 at least one cased character inS, False otherwise.186 “””

187 return False188

189 def join(self, iterable):190 “”” 连接 “””

191 “””

192 S.join(iterable) ->string193

194 Return a string which is the concatenation of the strings inthe195 iterable. The separator between elements isS.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]) ->string203

204 Return S left-justified in a string of length width. Padding is

205 done using the specified fill character (default isa space).206 “””

207 return “”208

209 def lower(self):210 “”” 变小写 “””

211 “””

212 S.lower() ->string213

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 orunicode222

223 Return a copy of the string S with leading whitespace removed.224 If chars is given and not None, remove characters inchars instead.225 If chars isunicode, S will be converted to unicode before stripping226 “””

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 returnthe part before it,235 the separator itself, and the part after it. If the separator is not

236 found, return S andtwo empty strings.237 “””

238 pass239

240 def replace(self, old, new, count=None):241 “”” 替换 “””

242 “””

243 S.replace(old, new[, count]) ->string244

245 Return a copy of string S with all occurrences of substring246 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]]) ->int254

255 Return the highest index in S where substring sub isfound,256 such that sub iscontained within S[start:end]. Optional257 arguments start and end are interpreted as inslice notation.258

259 Return -1on failure.260 “””

261 return 0262

263 def rindex(self, sub, start=None, end=None):264 “””

265 S.rindex(sub [,start [,end]]) ->int266

267 Like S.rfind() but raise ValueError when the substring is notfound.268 “””

269 return 0270

271 def rjust(self, width, fillchar=None):272 “””

273 S.rjust(width[, fillchar]) ->string274

275 Return S right-justified in a string of length width. Padding is

276 done using the specified fill character (default isa 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, andthe part after it. If the286 separator is not found, return two empty strings andS.287 “””

288 pass289

290 def rsplit(self, sep=None, maxsplit=None):291 “””

292 S.rsplit([sep [,maxsplit]]) ->list of strings293

294 Return a list of the words inthe string S, using sep as the295 delimiter string, starting at the end of the string andworking296 to the front. If maxsplit isgiven, at most maxsplit splits are297 done. If sep is not specified or isNone, any whitespace string298 isa separator.299 “””

300 return []301

302 def rstrip(self, chars=None):303 “””

304 S.rstrip([chars]) -> string orunicode305

306 Return a copy of the string S with trailing whitespace removed.307 If chars is given and not None, remove characters inchars instead.308 If chars isunicode, S will be converted to unicode before stripping309 “””

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 strings316

317 Return a list of the words inthe string S, using sep as the318 delimiter string. If maxsplit isgiven, at most maxsplit319 splits are done. If sep is not specified or isNone, any320 whitespace string is a separator andempty strings are removed321 fromthe 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 strings329

330 Return a list of the lines inS, breaking at line boundaries.331 Line breaks are not included inthe resulting list unless keepends332 is given andtrue.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]]) ->bool340

341 Return True ifS 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 False347

348 def strip(self, chars=None):349 “”” 移除两段空白 “””

350 “””

351 S.strip([chars]) -> string orunicode352

353 Return a copy of the string S with leading andtrailing354 whitespace removed.355 If chars is given and not None, remove characters inchars instead.356 If chars isunicode, S will be converted to unicode before stripping357 “””

358 return “”359

360 def swapcase(self):361 “”” 大写变小写,小写变大写 “””

362 “””

363 S.swapcase() ->string364

365 Return a copy of the string S with uppercase characters366 converted to lowercase andvice versa.367 “””

368 return “”369

370 def title(self):371 “””

372 S.title() ->string373

374 Return a titlecased version of S, i.e. words start with uppercase375 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]) ->string391

392 Return a copy of the string S, where all characters occurring393 in the optional argument deletechars are removed, andthe394 remaining characters have been mapped through the given395 translation table, which must be a string of length 256 orNone.396 If the table argument is None, no translation is applied and

397 the operation simply removes the characters indeletechars.398 “””

399 return “”400

401 def upper(self):402 “””

403 S.upper() ->string404

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) ->string413

414 Pad a numeric string S with zeros on the left, to fill a field415 of the specified width. The string S isnever truncated.416 “””

417 return “”418

419 def _formatter_field_name_split(self, *args, **kwargs): # real signature unknown420 pass421

422 def _formatter_parser(self, *args, **kwargs): # real signature unknown423 pass424

425 def __add__(self, y):426 “”” x.__add__(y) <==> x+y “””

427 pass428

429 def __contains__(self, y):430 “”” x.__contains__(y) <==> y in x “””

431 pass432

433 def __eq__(self, y):434 “”” x.__eq__(y) <==> x==y “””

435 pass436

437 def __format__(self, format_spec):438 “””

439 S.__format__(format_spec) ->string440

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 pass448

449 def __getitem__(self, y):450 “”” x.__getitem__(y) <==> x[y] “””

451 pass452

453 def __getnewargs__(self, *args, **kwargs): # real signature unknown454 pass455

456 def __getslice__(self, i, j):457 “””

458 x.__getslice__(i, j) <==>x[i:j]459

460 Use of negative indices is notsupported.461 “””

462 pass463

464 def __ge__(self, y):465 “”” x.__ge__(y) <==> x>=y “””

466 pass467

468 def __gt__(self, y):469 “”” x.__gt__(y) <==> x>y “””

470 pass471

472 def __hash__(self):473 “”” x.__hash__() <==> hash(x) “””

474 pass475

476 def __init__(self, string=”): # known special case of str.__init__477 “””

478 str(object=”) ->string479

480 Return a nice string representation of the object.481 If the argument is a string, the return value isthe same object.482 #(copied from class doc)

483 “””

484 pass485

486 def __len__(self):487 “”” x.__len__() <==> len(x) “””

488 pass489

490 def __le__(self, y):491 “”” x.__le__(y) <==> x<=y “””

492 pass493

494 def __lt__(self, y):495 “”” x.__lt__(y) <==> x

496 pass497

498 def __mod__(self, y):499 “”” x.__mod__(y) <==> x%y “””

500 pass501

502 def __mul__(self, n):503 “”” x.__mul__(n) <==> x*n “””

504 pass505

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 pass510

511 def __ne__(self, y):512 “”” x.__ne__(y) <==> x!=y “””

513 pass514

515 def __repr__(self):516 “”” x.__repr__() <==> repr(x) “””

517 pass518

519 def __rmod__(self, y):520 “”” x.__rmod__(y) <==> y%x “””

521 pass522

523 def __rmul__(self, n):524 “”” x.__rmul__(n) <==> n*x “””

525 pass526

527 def __sizeof__(self):528 “”” S.__sizeof__() -> size of S in memory, in bytes “””

529 pass530

531 def __str__(self):532 “”” x.__str__() <==> str(x) “””

533 pass534

535 str536

537 str

str

具体使用特别列出来了几个:

1 name=”tianjie”

2 print(type(name)) #显示数据是什么类型

3

4 name=”tianjie”

5 names=name.__contains__(“jie”) #字符“jie” 是否在对象中

6

7 name=”asdasdasdasdasdasd”

8 names=name.count(“as”,0,9) #统计在对象0-9索引中“as”字符有几个

9 print(names)10

11 name=”tianjie”

12 names=name.center(20,”*”) #宽数20居中,并且两边是“*”默认是空

13 print(names)14

15 name=”田杰”

16 names=name.encode(“gbk”) #转换字符编码

17 print(names)18

19 name=”tianjie”

20 names=name.capitalize() #首字母改为大写

21 names=name.endswith(“ie”,0,8) #0-8索引“ie”结尾

22 print(names)23

24 name=”tianjie”

25 #names=name.find(“j”) # #查找“j”在对象中的第一个下标

26 names=name.find(“an”)27 print(names)

name=”tianjieandxiaobai”

names=name.partition(“and”) #把对象name以“and” 为中心分成三段

print(names)

name=”asdfasdfasdfasdfasdsa”

names=name.replace(“a”,”w”) #把对象name中的”a”全部替换成”w”

names=name.replace(“a”,”w”,3) #把对象name中的“a”前三个替换成“w”

print(names)

万恶的字符串拼接就是“+”:

python中的字符串在C语言中体现为是一个字符数组,每次创建字符串时候需要在内存中开辟一块连续的空,并且一旦需要修改字符串的话,就需要再次开辟空间,万恶的+号每出现一次就会在内从中重新开辟一块空间。

字符串格式化:

1 name = input(“name:”)2 age = input(“age:”)3 job = input(“job:”)4

5 #print(“Infomation of []:” + name + “\nName:[]” + name +”\nAge:[]” + age +”\nJob:[]”+ job )#万恶的“+” 说的就是这个

6 #print(“Infomation of :%s\nName:%s\n\nJob:%s” %(name,name,age,job)) #土鳖写法格式

7

8 test = ”’

9 Infomation of :%s10 Name:%s11 age:%s12 Job:%s13 ”’ %(name,name,age,job) #这种写法格式才是高大上

14 print(test)

4、列表 *

书写格式如:[1,2,3,”qwe”,[123,”q”]],列表里可以包含任何数据,数字、字符、变量、也可以包含列表、字典、元组等。

序列都可以进行的操作包括索引,切片,加,乘,检查成员,而且是有序的

功能如下:

ContractedBlock.gif

ExpandedBlockStart.gif

1 classlist(object):2 “””

3 list() -> new empty list4 list(iterable) -> new list initialized from iterable’s items5 “””

6 def append(self, p_object): #real signature unknown; restored from __doc__

7 “””L.append(object) — append object to end”””

8 pass

9

10 def count(self, value): #real signature unknown; restored from __doc__

11 “””L.count(value) -> integer — return number of occurrences of value”””

12 return013

14 def extend(self, iterable): #real signature unknown; restored from __doc__

15 “””L.extend(iterable) — extend list by appending elements from the iterable”””

16 pass

17

18 def index(self, value, start=None, stop=None): #real signature unknown; restored from __doc__

19 “””

20 L.index(value, [start, [stop]]) -> integer — return first index of value.21 Raises ValueError if the value is not present.22 “””

23 return024

25 def insert(self, index, p_object): #real signature unknown; restored from __doc__

26 “””L.insert(index, object) — insert object before index”””

27 pass

28

29 def pop(self, index=None): #real signature unknown; restored from __doc__

30 “””

31 L.pop([index]) -> item — remove and return item at index (default last).32 Raises IndexError if list is empty or index is out of range.33 “””

34 pass

35

36 def remove(self, value): #real signature unknown; restored from __doc__

37 “””

38 L.remove(value) — remove first occurrence of value.39 Raises ValueError if the value is not present.40 “””

41 pass

42

43 def reverse(self): #real signature unknown; restored from __doc__

44 “””L.reverse() — reverse *IN PLACE*”””

45 pass

46

47 def sort(self, cmp=None, key=None, reverse=False): #real signature unknown; restored from __doc__

48 “””

49 L.sort(cmp=None, key=None, reverse=False) — stable sort *IN PLACE*;50 cmp(x, y) -> -1, 0, 151 “””

52 pass

53

54 def __add__(self, y): #real signature unknown; restored from __doc__

55 “””x.__add__(y) <==> x+y”””

56 pass

57

58 def __contains__(self, y): #real signature unknown; restored from __doc__

59 “””x.__contains__(y) <==> y in x”””

60 pass

61

62 def __delitem__(self, y): #real signature unknown; restored from __doc__

63 “””x.__delitem__(y) <==> del x[y]”””

64 pass

65

66 def __delslice__(self, i, j): #real signature unknown; restored from __doc__

67 “””

68 x.__delslice__(i, j) <==> del x[i:j]69

70 Use of negative indices is not supported.71 “””

72 pass

73

74 def __eq__(self, y): #real signature unknown; restored from __doc__

75 “””x.__eq__(y) <==> x==y”””

76 pass

77

78 def __getattribute__(self, name): #real signature unknown; restored from __doc__

79 “””x.__getattribute__(‘name’) <==> x.name”””

80 pass

81

82 def __getitem__(self, y): #real signature unknown; restored from __doc__

83 “””x.__getitem__(y) <==> x[y]”””

84 pass

85

86 def __getslice__(self, i, j): #real signature unknown; restored from __doc__

87 “””

88 x.__getslice__(i, j) <==> x[i:j]89

90 Use of negative indices is not supported.91 “””

92 pass

93

94 def __ge__(self, y): #real signature unknown; restored from __doc__

95 “””x.__ge__(y) <==> x>=y”””

96 pass

97

98 def __gt__(self, y): #real signature unknown; restored from __doc__

99 “””x.__gt__(y) <==> x>y”””

100 pass

101

102 def __iadd__(self, y): #real signature unknown; restored from __doc__

103 “””x.__iadd__(y) <==> x+=y”””

104 pass

105

106 def __imul__(self, y): #real signature unknown; restored from __doc__

107 “””x.__imul__(y) <==> x*=y”””

108 pass

109

110 def __init__(self, seq=()): #known special case of list.__init__

111 “””

112 list() -> new empty list113 list(iterable) -> new list initialized from iterable’s items114 # (copied from class doc)115 “””

116 pass

117

118 def __iter__(self): #real signature unknown; restored from __doc__

119 “””x.__iter__() <==> iter(x)”””

120 pass

121

122 def __len__(self): #real signature unknown; restored from __doc__

123 “””x.__len__() <==> len(x)”””

124 pass

125

126 def __le__(self, y): #real signature unknown; restored from __doc__

127 “””x.__le__(y) <==> x<=y”””

128 pass

129

130 def __lt__(self, y): #real signature unknown; restored from __doc__

131 “””x.__lt__(y) <==> x

132 pass

133

134 def __mul__(self, n): #real signature unknown; restored from __doc__

135 “””x.__mul__(n) <==> x*n”””

136 pass

137

138 @staticmethod #known case of __new__

139 def __new__(S, *more): #real signature unknown; restored from __doc__

140 “””T.__new__(S, …) -> a new object with type S, a subtype of T”””

141 pass

142

143 def __ne__(self, y): #real signature unknown; restored from __doc__

144 “””x.__ne__(y) <==> x!=y”””

145 pass

146

147 def __repr__(self): #real signature unknown; restored from __doc__

148 “””x.__repr__() <==> repr(x)”””

149 pass

150

151 def __reversed__(self): #real signature unknown; restored from __doc__

152 “””L.__reversed__() — return a reverse iterator over the list”””

153 pass

154

155 def __rmul__(self, n): #real signature unknown; restored from __doc__

156 “””x.__rmul__(n) <==> n*x”””

157 pass

158

159 def __setitem__(self, i, y): #real signature unknown; restored from __doc__

160 “””x.__setitem__(i, y) <==> x[i]=y”””

161 pass

162

163 def __setslice__(self, i, j, y): #real signature unknown; restored from __doc__

164 “””

165 x.__setslice__(i, j, y) <==> x[i:j]=y166

167 Use of negative indices is not supported.168 “””

169 pass

170

171 def __sizeof__(self): #real signature unknown; restored from __doc__

172 “””L.__sizeof__() — size of L in memory, in bytes”””

173 pass

174

175 __hash__ =None176

177 list

list

具体用法:

1 name=[1,2,3]2 name.extend([“g”,”k”,]) #合并,也可以合并一个列表

3

4 k=name.pop(0) #取出指定索引的元素,默认是最后一个元素,把取出来的元素在重新赋值

5 print(k)6

7 name=[1,2,3,”q”,”a”]8 name.reverse() #翻转,顺序颠倒

9

10 name.append(“tianjie”) #追加,在末尾添加

11

12 name.remove(“a”) #指定删除哪个元素

13

14 name.insert(3,”xiaobai”) #在指定下标后添加

15

16 name.index(“q”) #取出指定下标

17

18 name.count(“a”) #统计a在列表name中出现的次数

19

20 namel.sort() #排序,但是字符转不能与数字在一起排序

21

22 name.clear() #清空列表

23

24 name.copy() #复制,这里的复制指的是浅复制

实例1练习:

ContractedBlock.gif

ExpandedBlockStart.gif

1 创建个列表2 name=[“潘文斌”,”田杰”,”杩栋胜”,”潘东林”,”牛恒博”,”杜保强”,”梁连”,”赵鸿飞”]3

4 #新添加元素

5 name.insert(4,”张三”)6 name.insert(5,”李四”)7

8 #取出第3-8之间的人

9 print(name[2:8])10

11 #一次删除新添的两个名字

12 for i in name[4:6]:13 name.remove(i)14 print(name)15 #或者del name[4:6]

16

17 #删除第7个人

18 name.pop(7)19

20 #更改元素

21 name[0]=”潘文斌组长”

22 #隔一个人打印一个人

23 print(name[::2])

View Code

练习2:

创建列表如:

name=[6,6,4,564,5,6,56,45,6,45,64,56,45,6,655,5,56,2,2,2,34,2,34,6,6,4,4,4,4,5,5]1、把列表中数字6全部换成66662、把列表中数字4全部删掉

ContractedBlock.gif

ExpandedBlockStart.gif

1 name=[6,6,4,564,5,6,56,45,6,45,64,56,45,6,655,5,56,2,2,2,34,2,34,6,6,4,4,4,4,5,5]2 count=name.count(6)3

4 for i in range(name.count(6)):5 nums=name.index(6)6 name[nums]=6666

7

8 for i in range(name.count(4)):9 nums1=name.index(4)10 name.pop(nums1)11

12 print(name)

View Code

练习3:

练习:元素分类

有如下值集合 [11,22,33,44,55,66,77,88,99,90…],将所有大于 66 的值保存至字典的第一个key中,将小于 66的值保存至第二个key的值中。

即: {‘k1’: 大于66 , ‘k2’: 小于66}

ContractedBlock.gif

ExpandedBlockStart.gif

1 li=[11,22,33,44,55,66,77,88,99]2 dic={}3 a=[]4 b=[]5 for i inli:6 if i>66:7 a.append(i)8 else:9 b.append(1)10 dic[“k1”]=a11 dic[“k2”]=b12 print(dic)

View Code

5、元组

我的理解就是,不能修改,添加,删除的列表

书写格式:(“qwe”,”asd”,1,2,3,4)

功能如下:

ContractedBlock.gif

ExpandedBlockStart.gif

1 classtuple(object):2 “””

3 tuple() -> empty tuple4 tuple(iterable) -> tuple initialized from iterable’s items5

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 return011

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 return018

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 tuple65 tuple(iterable) -> tuple initialized from iterable’s items66

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

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

112

113 tuple

tuple

常用的工就两个:

1 name=(1,2,3,4,”q”,”e”,”c”)2 name.index(“q”) #查看下标

3 name.count(“e”) #统计

6、字典

字典的每个键值(key=>value)对用冒号(:)分割,每个对之间用逗号(,)分割,整个字典包括在花括号({})中,格式如下:

{“name”:”tianjie”,”age”:18}

{“host”:’192.168.1.2′,”port”:80}

注:循环时默认循环key

功能如下:

ContractedBlock.gif

ExpandedBlockStart.gif

1 classdict(object):2 “””

3 dict() -> new empty dictionary4 dict(mapping) -> new dictionary initialized from a mapping object’s5 (key, value) pairs6 dict(iterable) -> new dictionary initialized as if via:7 d = {}8 for k, v in iterable:9 d[k] = v10 dict(**kwargs) -> new dictionary initialized with the name=value pairs11 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 python3中移除”””

39 “””D.has_key(k) -> True if D has a key k, else False”””

40 returnFalse41

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 raised72 “””

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 a79 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] = v97 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 returnFalse126

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 dictionary154 dict(mapping) -> new dictionary initialized from a mapping object’s155 (key, value) pairs156 dict(iterable) -> new dictionary initialized as if via:157 d = {}158 for k, v in iterable:159 d[k] = v160 dict(**kwargs) -> new dictionary initialized with the name=value pairs161 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

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__ =None204

205 dict

dict

具体用法:

id_db={123:{“name”:”tianjie”,”age”:12,”job”:”IT”,

},345:{“name”:”xiaobai”,”age”:13,”job”:”IT”,

},

}#id_db[123][“name”]=”xiaohei” #修改#print(id_db)

#id_db[345][“xingbie”]=”nan” #添加#print(id_db)

#id_db[123].pop(“age”) #删除## del id_db[123][“name”]## print(id_db)

##d=id_db.get(123) #取值 没有值,也不报错#d=id_db.get(456)#print(d)

#dic2={#”name”:”xiaoma”,#”age”:18,#”job”:”IT”,#}#id_db.update(dic2) #覆盖,有就覆盖,不存在添加新的#print(id_db)

#print(id_db.keys()) #取key#print(id_db.values())#取元素

print(dict.fromkeys([1,2,3,4],’ddd’))#把后面的ddd做元素分别赋值给前面的列表生成字典(据说里面有坑)

dic1 = {

‘alex’:’good’,

‘wuSIR’:’good’,

‘wb’:’DSB’

}

for i in dic1:

print(i)

#循环取得是key

#输出结果为:

alex

wuSIR

wb

print(len(dic1)) #计算字典元素个数,即键的总数

print(str(dic1)) #输出字典以可打印的字符串表示

print(type(dic1)) #返回输入的变量类型,如果变量是字典就返回字典类型

练习:

练习:元素分类

有如下值集合 [11,22,33,44,55,66,77,88,99,90…],将所有大于 66 的值保存至字典的第一个key中,将小于 66的值保存至第二个key的值中。

即: {‘k1’: 大于66 , ‘k2’: 小于66}

ContractedBlock.gif

ExpandedBlockStart.gif

1 li=[11,22,33,44,55,66,77,88,99]2 dic={}3 for i inli:4 if i>66:5 if “k1” indic.keys():6 dic[“k1”].append(i)7 else:8 dic[“k1”]=[i,]9 else:10 if “k2” indic.keys():11 dic[“k2”].append(i)12 else:13 dic[“k2”] =[i,]14 print(dic)

View Code

ContractedBlock.gif

ExpandedBlockStart.gif

1 num=[11,22,33,44,55,66,77,88,99]2 name=collections.defaultdict(list) #指定了默认字典

3 for i innum:4 if i >66:5 name[“k1”].append(i)6 else:7 name[“k2”].append(i)8 print(name)

View Code

7、set集合:

首先说set的是什么?

set是一个无序的,不可重复的元组集合,也可嵌套。

创建集合:

se={1,2,3,4}

se=set(1,2,3,4)

se=set([1,2,3,4,”q”,”a”])

集合都有哪些功能:

ContractedBlock.gif

ExpandedBlockStart.gif

1 classset(object):2 “””

3 set() -> new empty set object4 set(iterable) -> new set object5

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,添加元素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. 清除内容”””

18 pass

19

20 def copy(self, *args, **kwargs): #real signature unknown

21 “””Return a shallow copy of a set. 浅拷贝”””

22 pass

23

24 def difference(self, *args, **kwargs): #real signature unknown

25 “””

26 Return the difference of two or more sets as a new set. A中存在,B中不存在27

28 (i.e. all elements that are in this set but not the others.)29 “””

30 pass

31

32 def difference_update(self, *args, **kwargs): #real signature unknown

33 “””Remove all elements of another set from this set. 从当前集合中删除和B中相同的元素”””

34 pass

35

36 def discard(self, *args, **kwargs): #real signature unknown

37 “””

38 Remove an element from a set if it is a member.39

40 If the element is not a member, do nothing. 移除指定元素,不存在不保错41 “””

42 pass

43

44 def intersection(self, *args, **kwargs): #real signature unknown

45 “””

46 Return the intersection of two sets as a new set. 交集47

48 (i.e. all elements that are in both sets.)49 “””

50 pass

51

52 def intersection_update(self, *args, **kwargs): #real signature unknown

53 “””Update a set with the intersection of itself and another. 取交集并更更新到A中”””

54 pass

55

56 def isdisjoint(self, *args, **kwargs): #real signature unknown

57 “””Return True if two sets have a null intersection. 如果没有交集,返回True,否则返回False”””

58 pass

59

60 def issubset(self, *args, **kwargs): #real signature unknown

61 “””Report whether another set contains this set. 是否是子序列”””

62 pass

63

64 def issuperset(self, *args, **kwargs): #real signature unknown

65 “””Report whether this set contains another set. 是否是父序列”””

66 pass

67

68 def pop(self, *args, **kwargs): #real signature unknown

69 “””

70 Remove and return an arbitrary set element.71 Raises KeyError if the set is empty. 移除元素72 “””

73 pass

74

75 def remove(self, *args, **kwargs): #real signature unknown

76 “””

77 Remove an element from a set; it must be a member.78

79 If the element is not a member, raise a KeyError. 移除指定元素,不存在保错80 “””

81 pass

82

83 def symmetric_difference(self, *args, **kwargs): #real signature unknown

84 “””

85 Return the symmetric difference of two sets as a new set. 对称差集86

87 (i.e. all elements that are in exactly one of the sets.)88 “””

89 pass

90

91 def symmetric_difference_update(self, *args, **kwargs): #real signature unknown

92 “””Update a set with the symmetric difference of itself and another. 对称差集,并更新到a中”””

93 pass

94

95 def union(self, *args, **kwargs): #real signature unknown

96 “””

97 Return the union of sets as a new set. 并集98

99 (i.e. all elements that are in either set.)100 “””

101 pass

102

103 def update(self, *args, **kwargs): #real signature unknown

104 “””Update a set with the union of itself and others. 更新”””

105 pass

set

具体用法:

1 name=set() #定义集合

2 name.add(“tianjie”) #添加集合

3 print(name)4 name.update([“k1″,”a1″,”a2″,”a3”])#更新

5 print(name)6

7 name1=set([“k2″,”k3″,”k4″,”a1”])8 print(name1)9 name2=name1.difference(name) #取变量name1中,name变量中不存在的元素生成一个新的set

10 print(name2)11

12 name3=set([“v1″,”v2″,”v3″,”v4”])13 print(name3)14

15 name4=name3.intersection([“v1″,”d1″,”v0″,”v2”])#取交集生成新的set or name4=name3.intersection(name1) 里面也可以是另一个集合变量

16 print(name4)17

18 name3.intersection_update(name4)#取交集修改原来的set 就是把原来name3替换成交集的结果

19 print(name3)20

21 print(name3.isdisjoint(name4)) #如果name3和name4是否有交集 没有则返回True 有就返回False

22 print(name3.issuperset(name4))#是name3是否是name4父集,是就为True ,就是name3是否包含name4

23 name4=name3.pop() #移除一个元素,获取到移除的元素,注意这是随机的

24 print(name3)25 print(name4)26

27 name3.remove(“v2”) #移除指定元素,没有就报错

28 print(name3)29

30 name3.discard(“v2”) #移除指定元素,没有也不报错

实例练习:

寻找差异:

#数据库中原有

old_dict ={“#1″:{ ‘hostname’:c1, ‘cpu_count’: 2, ‘mem_capicity’: 80},”#2″:{ ‘hostname’:c1, ‘cpu_count’: 2, ‘mem_capicity’: 80}”#3”:{ ‘hostname’:c1, ‘cpu_count’: 2, ‘mem_capicity’: 80}

}#cmdb 新汇报的数据

new_dict ={“#1″:{ ‘hostname’:c1, ‘cpu_count’: 2, ‘mem_capicity’: 800},”#3″:{ ‘hostname’:c1, ‘cpu_count’: 2, ‘mem_capicity’: 80}”#4”:{ ‘hostname’:c2, ‘cpu_count’: 2, ‘mem_capicity’: 80}

}

列出需要删除,需要添加,需要更新的项,

无需考虑内部元素是否改变,只要原来存在,新汇报也存在,就是需要更新

1 需要添加的项:2 就是新的有(new_dict),旧的没有的项(old_dict)添加3 代码:4 A=set(old_dict)5 B=set(new_dict)6 s1=B.difference(A)7 需要删除的项:8 就是旧的有,新的没有 删除9 代码:10 s2=A.difference(B)11 需要更新的项:12 就是旧的有,新的也有 就是需要更新的13 s3=A.intersection(B)

集合简写(特殊字符代替):

1 name1=set([“v1″,”v2″,”v3″,”v4”])2 print(name1)3 name2=set([“v1″,”v2″,”a”,”a1″,”v6″])4 print(name2)5 print(name1&name2) #交集

6 print(name1|name2) #并集

7 print(name1-name2)#差集显示name1差集,name1有name2没有

8 print(name2-name1)#差集显示name2差集,name2有name1没有

9 print(name1^name2)#求对称差集,name1没有name2的,name2中的没有name1的

以上输出结果:

1 C:\Python\Python35\python.exe D:/学习功课/s13/day3/set集合.py2 {‘v1’, ‘v2’, ‘v4’, ‘v3’}3 {‘a1’, ‘v1’, ‘a’, ‘v2’, ‘v6’}4 {‘v1’, ‘v2’}5 {‘v4’, ‘v2’, ‘v6’, ‘a1’, ‘v1’, ‘v3’, ‘a’}6 {‘v4’, ‘v3’}7 {‘a1’, ‘a’, ‘v6’}8 {‘v4’, ‘v6’, ‘a1’, ‘v3’, ‘a’}9

10 Process finished with exit code 0