day2

 1 name.capitalize()  首字母大写
 2 name.casefold()   大写全部变小写
 3 name.center(50,"-")  输出 ‘---------------------Alex Li----------------------‘
 4 name.count(‘lex‘) 统计 lex出现次数
 5 name.encode()  将字符串编码成bytes格式
 6 name.endswith("Li")  判断字符串是否以 Li结尾
 7  "Alex\tLi".expandtabs(10) 输出‘Alex      Li‘， 将\t转换成多长的空格 
 8  name.find(‘A‘)  查找A,找到返回其索引， 找不到返回-1 
 9 
10 format :
11     >>> msg = "my name is {}, and age is {}"
12     >>> msg.format("alex",22)
13     ‘my name is alex, and age is 22‘
14     >>> msg = "my name is {1}, and age is {0}"
15     >>> msg.format("alex",22)
16     ‘my name is 22, and age is alex‘
17     >>> msg = "my name is {name}, and age is {age}"
18     >>> msg.format(age=22,name="ale")
19     ‘my name is ale, and age is 22‘
20 format_map
21     >>> msg.format_map({‘name‘:‘alex‘,‘age‘:22})
22     ‘my name is alex, and age is 22‘
23 
24 
25 msg.index(‘a‘)  返回a所在字符串的索引
26 ‘9aA‘.isalnum()   True
27 
28 ‘9‘.isdigit() 是否整数
29 name.isnumeric  
30 name.isprintable
31 name.isspace
32 name.istitle
33 name.isupper
34  "|".join([‘alex‘,‘jack‘,‘rain‘])
35 ‘alex|jack|rain‘
36 
37 
38 maketrans
39     >>> intab = "aeiou"  #This is the string having actual characters. 
40     >>> outtab = "12345" #This is the string having corresponding mapping character
41     >>> trantab = str.maketrans(intab, outtab)
42     >>> 
43     >>> str = "this is string example....wow!!!"
44     >>> str.translate(trantab)
45     ‘th3s 3s str3ng 2x1mpl2....w4w!!!‘
46 
47  msg.partition(‘is‘)   输出 (‘my name ‘, ‘is‘, ‘ {name}, and age is {age}‘) 
48 
49  >>> "alex li, chinese name is lijie".replace("li","LI",1)
50      ‘alex LI, chinese name is lijie‘
51 
52  msg.swapcase 大小写互换
53 
54 
55  >>> msg.zfill(40)
56 ‘00000my name is {name}, and age is {age}‘
57 
58 
59 
60 >>> n4.ljust(40,"-")
61 ‘Hello 2orld-----------------------------‘
62 >>> n4.rjust(40,"-")
63 ‘-----------------------------Hello 2orld‘
64 
65 
66 >>> b="ddefdsdff_哈哈" 
67 >>> b.isidentifier() #检测一段字符串可否被当作标志符，即是否符合变量命名规则
68 True

1 info = {
2     ‘stu1101‘: "TengLan Wu",
3     ‘stu1102‘: "LongZe Luola",
4     ‘stu1103‘: "XiaoZe Maliya",
5 }

1 >>> info["stu1104"] = "苍井空"
2 >>> info
3 {‘stu1102‘: ‘LongZe Luola‘, ‘stu1104‘: ‘苍井空‘, ‘stu1103‘: ‘XiaoZe Maliya‘, ‘stu1101‘: ‘TengLan Wu‘}

 1 >>> info
 2 {‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘, ‘stu1101‘: ‘武藤兰‘}
 3 >>> info.pop("stu1101") #标准删除姿势
 4 ‘武藤兰‘
 5 >>> info
 6 {‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘}
 7 >>> del info[‘stu1103‘] #换个姿势删除
 8 >>> info
 9 {‘stu1102‘: ‘LongZe Luola‘}
10 >>> 
11 >>> 
12 >>> 
13 >>> info = {‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘}
14 >>> info
15 {‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘} #随机删除
16 >>> info.popitem()
17 (‘stu1102‘, ‘LongZe Luola‘)
18 >>> info
19 {‘stu1103‘: ‘XiaoZe Maliya‘}

 1 >>> info = {‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘}
 2 >>> 
 3 >>> "stu1102" in info #标准用法
 4 True
 5 >>> info.get("stu1102")  #获取
 6 ‘LongZe Luola‘
 7 >>> info["stu1102"] #同上，但是看下面
 8 ‘LongZe Luola‘
 9 >>> info["stu1105"]  #如果一个key不存在，就报错，get不会，不存在只返回None
10 Traceback (most recent call last):
11   File "<stdin>", line 1, in <module>
12 KeyError: ‘stu1105‘

1 #方法1
2 for key in info:
3     print(key,info[key])
4 
5 #方法2
6 for k,v in info.items(): #会先把dict转成list,数据里大时莫用
7     print(k,v)

 1 s = set([3,5,9,10])      #创建一个数值集合  
 2   
 3 t = set("Hello")         #创建一个唯一字符的集合  
 4 
 5 
 6 a = t | s          # t 和 s的并集  
 7   
 8 b = t & s          # t 和 s的交集  
 9   
10 c = t – s          # 求差集（项在t中，但不在s中）  
11   
12 d = t ^ s          # 对称差集（项在t或s中，但不会同时出现在二者中）  
13   
14    
15   
16 基本操作：  
17   
18 t.add(‘x‘)            # 添加一项  
19   
20 s.update([10,37,42])  # 在s中添加多项  
21   
22    
23   
24 使用remove()可以删除一项：  
25   
26 t.remove(‘H‘)  
27   
28   
29 len(s)  
30 set 的长度  
31   
32 x in s  
33 测试 x 是否是 s 的成员  
34   
35 x not in s  
36 测试 x 是否不是 s 的成员  
37   
38 s.issubset(t)  
39 s <= t  
40 测试是否 s 中的每一个元素都在 t 中  
41   
42 s.issuperset(t)  
43 s >= t  
44 测试是否 t 中的每一个元素都在 s 中  
45   
46 s.union(t)  
47 s | t  
48 返回一个新的 set 包含 s 和 t 中的每一个元素  
49   
50 s.intersection(t)  
51 s & t  
52 返回一个新的 set 包含 s 和 t 中的公共元素  
53   
54 s.difference(t)  
55 s - t  
56 返回一个新的 set 包含 s 中有但是 t 中没有的元素  
57   
58 s.symmetric_difference(t)  
59 s ^ t  
60 返回一个新的 set 包含 s 和 t 中不重复的元素  
61   
62 s.copy()  
63 返回 set “s”的一个浅复制

1 f = open(‘lyrics‘) #打开文件
2 first_line = f.readline()
3 print(‘first line:‘,first_line) #读一行
4 print(‘我是分隔线‘.center(50,‘-‘))
5 data = f.read()# 读取剩下的所有内容,文件大时不要用
6 print(data) #打印文件
7  
8 f.close() #关闭文件

 1 def close(self): # real signature unknown; restored from __doc__
 2         """
 3         Close the file.
 4         
 5         A closed file cannot be used for further I/O operations.  close() may be
 6         called more than once without error.
 7         """
 8         pass
 9 
10     def fileno(self, *args, **kwargs): # real signature unknown
11         """ Return the underlying file descriptor (an integer). """
12         pass
13 
14     def isatty(self, *args, **kwargs): # real signature unknown
15         """ True if the file is connected to a TTY device. """
16         pass
17 
18     def read(self, size=-1): # known case of _io.FileIO.read
19         """
20         注意，不一定能全读回来
21         Read at most size bytes, returned as bytes.
22         
23         Only makes one system call, so less data may be returned than requested.
24         In non-blocking mode, returns None if no data is available.
25         Return an empty bytes object at EOF.
26         """
27         return ""
28 
29     def readable(self, *args, **kwargs): # real signature unknown
30         """ True if file was opened in a read mode. """
31         pass
32 
33     def readall(self, *args, **kwargs): # real signature unknown
34         """
35         Read all data from the file, returned as bytes.
36         
37         In non-blocking mode, returns as much as is immediately available,
38         or None if no data is available.  Return an empty bytes object at EOF.
39         """
40         pass
41 
42     def readinto(self): # real signature unknown; restored from __doc__
43         """ Same as RawIOBase.readinto(). """
44         pass #不要用,没人知道它是干嘛用的
45 
46     def seek(self, *args, **kwargs): # real signature unknown
47         """
48         Move to new file position and return the file position.
49         
50         Argument offset is a byte count.  Optional argument whence defaults to
51         SEEK_SET or 0 (offset from start of file, offset should be >= 0); other values
52         are SEEK_CUR or 1 (move relative to current position, positive or negative),
53         and SEEK_END or 2 (move relative to end of file, usually negative, although
54         many platforms allow seeking beyond the end of a file).
55         
56         Note that not all file objects are seekable.
57         """
58         pass
59 
60     def seekable(self, *args, **kwargs): # real signature unknown
61         """ True if file supports random-access. """
62         pass
63 
64     def tell(self, *args, **kwargs): # real signature unknown
65         """
66         Current file position.
67         
68         Can raise OSError for non seekable files.
69         """
70         pass
71 
72     def truncate(self, *args, **kwargs): # real signature unknown
73         """
74         Truncate the file to at most size bytes and return the truncated size.
75         
76         Size defaults to the current file position, as returned by tell().
77         The current file position is changed to the value of size.
78         """
79         pass
80 
81     def writable(self, *args, **kwargs): # real signature unknown
82         """ True if file was opened in a write mode. """
83         pass
84 
85     def write(self, *args, **kwargs): # real signature unknown
86         """
87         Write bytes b to file, return number written.
88         
89         Only makes one system call, so not all of the data may be written.
90         The number of bytes actually written is returned.  In non-blocking mode,
91         returns None if the write would block.
92         """
93         pass