Python_02

Posted 2020-09-23

本节内容

• 列表、元组操作
• 字符串操作
• 字典操作

 1、列表、元组操作 

列表

列表是经常操作的数据形式之一，可以对列表对数据进行简单的增删改查等操作。

定义列表

1 names = [‘ZhangYang‘,‘Guyun‘,‘Xiangpeng‘,‘XuLiangchen‘]

通过下标访问列表中的元素，下标从0开始计数

1 >>> names[0]
2 ‘ZhangYang‘
3 >>> names[2]
4 ‘Xiangpeng‘
5 >>> names[-1]
6 ‘XuLiangchen‘
7 >>> names[-2] #倒序取
8 ‘Xiangpeng‘

切片，取多个元素

 1 >>> names = [‘ZhangYang‘,‘Guyun‘,‘Xiangpeng‘,‘Xmy‘,‘XuLiangchen‘]
 2 >>> names[1:3]
 3 [‘Guyun‘, ‘Xiangpeng‘]
 4 >>> names[1:-1]
 5 [‘Guyun‘, ‘Xiangpeng‘, ‘Xmy‘]
 6 >>> names[:3] #等同于names[0:3]
 7 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘]
 8 >>> names[3:]
 9 [‘Xmy‘, ‘XuLiangchen‘]
10 >>> names[0::2] #后面的2是代表，每隔一个元素，就取一个，等同于names[::2]
11 [‘ZhangYang‘, ‘Xiangpeng‘, ‘XuLiangchen‘]

View Code

追加

1 >>> names
2 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘Xmy‘, ‘XuLiangchen‘]
3 >>> names.append(‘LeiHaidong‘)
4 >>> names
5 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘Xmy‘, ‘XuLiangchen‘, ‘LeiHaidong‘]

View Code

插入

1 >>> names
2 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘Xmy‘, ‘XuLiangchen‘, ‘LeiHaidong‘]
3 >>> names.insert(2,‘flashman‘) #插入到位置2
4 >>> names
5 [‘ZhangYang‘, ‘Guyun‘, ‘flashman‘, ‘Xiangpeng‘, ‘Xmy‘, ‘XuLiangchen‘, ‘LeiHaidong‘]

View Code

修改

1 >>> names
2 [‘ZhangYang‘, ‘Guyun‘, ‘flashman‘, ‘Xiangpeng‘, ‘Xmy‘, ‘XuLiangchen‘, ‘LeiHaidong‘]
3 >>> names[2] = ‘oldman‘
4 >>> names
5 [‘ZhangYang‘, ‘Guyun‘, ‘oldman‘, ‘Xiangpeng‘, ‘Xmy‘, ‘XuLiangchen‘, ‘LeiHaidong‘]

View Code

删除

 1 >>> names
 2 [‘ZhangYang‘, ‘Guyun‘, ‘flashman‘, ‘Xiangpeng‘, ‘Xmy‘, ‘XuLiangchen‘, ‘LeiHaidong‘]
 3 >>> names[2] = ‘oldman‘
 4 >>> names
 5 [‘ZhangYang‘, ‘Guyun‘, ‘oldman‘, ‘Xiangpeng‘, ‘Xmy‘, ‘XuLiangchen‘, ‘LeiHaidong‘]
 6 >>> del names[2]
 7 >>> names
 8 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘Xmy‘, ‘XuLiangchen‘, ‘LeiHaidong‘]
 9 >>> names.remove(‘Xmy‘) #指定删除元素
10 >>> names
11 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘XuLiangchen‘, ‘LeiHaidong‘]
12 >>> names.pop() #删除最后一个值
13 ‘LeiHaidong‘
14 >>> names
15 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘XuLiangchen‘]

View Code

扩展

1 >>> names
2 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘XuLiangchen‘]
3 >>> names2 = [1,2,3,4]
4 >>> names.extend(names2)
5 >>> names
6 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘XuLiangchen‘, 1, 2, 3, 4]

View Code

拷贝

 1 >>> names
 2 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘XuLiangchen‘, 1, 2, 3, 4]
 3 >>> names_copy = names.copy() #浅拷贝
 4 >>> names_copy
 5 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘XuLiangchen‘, 1, 2, 3, 4]
 6 >>> 
 7 >>> names.insert(4,[‘Xmy‘,‘Zhb‘])
 8 >>> names
 9 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘XuLiangchen‘, [‘Xmy‘, ‘Zhb‘], 1, 2, 3, 4]
10 >>> names_copy = copy.copy(names) #浅拷贝
11 >>> names_copy2 = copy.deepcopy(names) #深拷贝
12 >>> names_copy
13 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘XuLiangchen‘, [‘Xmy‘, ‘Zhb‘], 1, 2, 3, 4]
14 >>> names_copy2
15 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘XuLiangchen‘, [‘Xmy‘, ‘Zhb‘], 1, 2, 3, 4]
16 >>> names[2]=‘向鹏‘
17 >>> names[4][0] = ‘xumengyuan‘
18 >>> names
19 [‘ZhangYang‘, ‘Guyun‘, ‘向鹏‘, ‘XuLiangchen‘, [‘xumengyuan‘, ‘Zhb‘], 1, 2, 3, 4]
20 >>> names_copy
21 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘XuLiangchen‘, [‘xumengyuan‘, ‘Zhb‘], 1, 2, 3, 4]
22 >>> names_copy2
23 [‘ZhangYang‘, ‘Guyun‘, ‘Xiangpeng‘, ‘XuLiangchen‘, [‘Xmy‘, ‘Zhb‘], 1, 2, 3, 4]

View Code

统计

1 >>> names
2 [‘ZhangYang‘, ‘Guyun‘, ‘向鹏‘, ‘XuLiangchen‘, [‘xumengyuan‘, ‘Zhb‘], ‘Guyun‘,1, 2, 3, 4]
3 >>> names.count(‘xumengyuan‘)
4 0
5 >>> names.count([‘xumengyuan‘, ‘Zhb‘])
6 1
7 >>> names.count(‘Guyun‘)
8 2

View Code

排序&反转

 1 >>> names
 2 [‘ZhangYang‘, ‘Guyun‘, ‘向鹏‘, ‘XuLiangchen‘, 1, 2, 3, 4]
 3 >>> names.sort() #排序
 4 Traceback (most recent call last):
 5   File "<input>", line 1, in <module>
 6 TypeError: unorderable types: list() < str() #3.0里不同数据类型不能放在一起排序了
 7 >>> names[-4:] = ‘1‘,‘2‘,‘3‘,‘4‘
 8 >>> names
 9 [‘ZhangYang‘, ‘Guyun‘, ‘向鹏‘, ‘XuLiangchen‘, ‘1‘, ‘2‘, ‘3‘, ‘4‘]
10 >>> names.sort()
11 >>> names
12 [‘1‘, ‘2‘, ‘3‘, ‘4‘, ‘Guyun‘, ‘XuLiangchen‘, ‘ZhangYang‘, ‘向鹏‘]
13 >>> names.reverse() #反转
14 >>> names
15 [‘向鹏‘, ‘ZhangYang‘, ‘XuLiangchen‘, ‘Guyun‘, ‘4‘, ‘3‘, ‘2‘, ‘1‘]

View Code

获取下标

1 >>> names
2 [‘向鹏‘, ‘ZhangYang‘, ‘XuLiangchen‘, ‘Guyun‘, ‘4‘, ‘3‘, ‘2‘, ‘1‘]
3 >>> names.index(‘3‘)
4 5

View Code

元组

元组其实跟列表差不多，也是存一组数，只不是它一旦创建，便不能再修改，所以又叫只读列表

1 names = (‘Alex‘,‘Jack‘)

它只有2个方法，一个是count,一个是index，完毕。　

　

 2、字符串操作 

特性：不可修改

 定义字符串

1 name = ‘My name is {name} and I am {year} old‘
2 name2 = ‘My \tname is {name} and I am {year} old‘

字符串相关函数

 1 >>> name.capitalize() #首字母大写
 2 ‘My name is {name} and i am {year} old‘
 3 >>> name.count(‘m‘) 统计m出现的次数
 4 3
 5 >>> name.center(50,‘-‘) #输出如下
 6 ‘------My name is {name} and I am {year} old-------‘
 7 >>> name.endswith(‘my‘) #判断字符串是否以my结尾
 8 False
 9 >>> name.expandtabs(tabsize=30) 
10 ‘My name is {name} and I am {year} old‘
11 >>> name2.expandtabs(tabsize=30) #将\t转换成多长的空格
12 ‘My                            name is {name} and I am {year} old‘
13 >>> name.find(‘name‘) #查找那么并返回其索引，找不到则返回-1
14 3
15 >>> name[name.find(‘name‘):9] #可以用find做切片
16 ‘name i‘
17 
18 #format
19 >>> msg = "my name is {}, and age is {}"
20 >>> msg.format("Xmy",23)
21 ‘My name is Xmy and I am 23‘
22 >>> msg = "my name is {1}, and age is {0}"
23 msg.format("Xmy",23)
24 ‘My name is 23 and I am Xmy‘
25 >>> msg = "my name is {name}, and age is {age}"
26 >>> msg.format(age=23,name="Xmy")
27 ‘my name is Xmy, and age is 23‘
28 #format_map
29 >>> name.format_map({‘name‘:‘Xmy‘,‘year‘:12})
30 ‘my name is Xmy, and age is 23‘
31 
32 
33 >>> ‘ab23‘.isalnum()
34 True
35 >>> ‘abA‘.isalpha()
36 True
37 >>> ‘1A‘.isdecimal()
38 False
39 >>> ‘1A‘.isdigit()
40 False
41 >>> ‘a1A‘.isidentifier() #判断是不是一个合法的标识符
42 True
43 >>> ‘33a‘.isnumeric()
44 False
45 >>> ‘ ‘.isspace()
46 True
47 >>> ‘My Name Is‘.istitle()
48 True
49 >>> ‘My Name Is‘.isprintable()
50 True
51 >>> ‘My Name Is‘.isupper()
52 False
53 >>> ‘+‘.join([‘1‘,‘2‘,‘3‘,‘4‘])
54 ‘1+2+3+4‘
55 >>> name.ljust(50,‘*‘)
56 ‘My name is {name} and I am {year} old*************‘
57 >>> name.rjust(50,‘*‘)
58 ‘*************My name is {name} and I am {year} old‘
59 >>> name.lower()
60 ‘my name is {name} and i am {year} old‘
61 >>> name.upper()
62 ‘MY NAME IS {NAME} AND I AM {YEAR} OLD‘
63 >>> ‘\nAlex‘.lstrip()
64 ‘Alex‘
65 >>> ‘Alex\n‘.rstrip()
66 ‘Alex‘
67 >>> ‘   Alex\n‘.strip()
68 ‘Alex‘
69 
70 #maketrans
71 >>> p = str.maketrans(‘abcdef‘,‘123456‘)
72 >>> ‘alex li‘.translate(p)
73 ‘1l5x li‘
74 
75 >>> ‘Alex li‘.replace(‘l‘,‘L‘,1)
76 ‘ALex li‘
77 >>> ‘alex li‘.rfind(‘l‘)
78 5
79 >>> ‘alex li‘.split(‘l‘)
80 [‘a‘, ‘ex ‘, ‘i‘]
81 >>> ‘alex\nli‘.splitlines()
82 [‘alex‘, ‘li‘]
83 >>> ‘Alex Li‘.swapcase() #大小写互换
84 ‘aLEX lI‘
85 >>> ‘alex li‘.title()
86 ‘Alex Li‘
87 >>> ‘alex‘.zfill(50)
88 ‘0000000000000000000000000000000000000000000000alex‘

View Code

 

 3、字符串操作 

 字典一种key - value 的数据类型，使用就像我们上学用的字典，通过笔划、字母来查对应页的详细内容。

语法：

info = {
    ‘stu1101‘:‘TengLan Wu‘,
    ‘stu1102‘:‘LongZe Luola‘,
    ‘stu1103‘:‘XiaoZe Maliya‘,
}

字典的特性：

• dict是无序的
• key必须是唯一的,so 天生去重

增加

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

View Code

修改

1 >>> info[‘stu1102‘] = ‘武藤兰‘
2 >>> info
3 {‘stu1101‘: ‘TengLan Wu‘, ‘stu1102‘: ‘武藤兰‘, ‘stu1103‘: ‘XiaoZe Maliya‘}

View Code

删除

 1 >>> info
 2 {‘stu1101‘: ‘TengLan Wu‘, ‘stu1102‘: ‘武藤兰‘, ‘stu1103‘: ‘XiaoZe Maliya‘}
 3 >>> info.pop(‘stu1101‘)
 4 ‘TengLan Wu‘
 5 >>> info
 6 {‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘}
 7 >>> del info[‘stu1102‘]
 8 >>> info
 9 {‘stu1103‘: ‘XiaoZe Maliya‘}
10 >>>
11 >>>
12 >>>info
13 {‘stu1101‘: ‘TengLan Wu‘, ‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘}
14 >>> info.popitem()
15 (‘stu1103‘, ‘XiaoZe Maliya‘)
16 >>> info
17 {‘stu1101‘: ‘TengLan Wu‘, ‘stu1102‘: ‘LongZe Luola‘}

View Code

查找

 1 >>> info
 2 {‘stu1101‘: ‘TengLan Wu‘, ‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘}
 3 >>> ‘stu1103‘ in info
 4 True
 5 >>> info.get(‘stu1103‘)
 6 ‘XiaoZe Maliya‘
 7 >>> info[‘stu1103‘]
 8 ‘XiaoZe Maliya‘
 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 "<input>", line 1, in <module>
12 KeyError: ‘stu1105‘

View Code

多级字典嵌套及操作

 1 >>> av_catalog = {
 2 ...     "欧美":{
 3 ...         "www.youporn.com": ["很多免费的,世界最大的","质量一般"],
 4 ...         "www.pornhub.com": ["很多免费的,也很大","质量比yourporn高点"],
 5 ...         "letmedothistoyou.com": ["多是自拍,高质量图片很多","资源不多,更新慢"],
 6 ...         "x-art.com":["质量很高,真的很高","全部收费,屌比请绕过"]
 7 ...     },
 8 ...     "日韩":{
 9 ...         "tokyo-hot":["质量怎样不清楚,个人已经不喜欢日韩范了","听说是收费的"]
10 ...     },
11 ...     "大陆":{
12 ...         "1024":["全部免费,真好,好人一生平安","服务器在国外,慢"]
13 ...     }
14 ... }
15 >>> av_catalog["大陆"]["1024"][1] += ",可以用爬虫爬下来"
16 >>> print(av_catalog["大陆"]["1024"])
17 [‘全部免费,真好,好人一生平安‘, ‘服务器在国外,慢,可以用爬虫爬下来‘]

View Code

其他

 1 #values
 2 >>> info.values()
 3 dict_values([‘TengLan Wu‘, ‘LongZe Luola‘, ‘XiaoZe Maliya‘])
 4 
 5 #keys
 6 >>> info.keys()
 7 dict_keys([‘stu1101‘, ‘stu1102‘, ‘stu1103‘])
 8 
 9 #setdefault
10 >>> info.setdefault(‘stu1101‘,‘SDASGA‘)
11 ‘TengLan Wu‘
12 >>> info
13 {‘stu1101‘: ‘TengLan Wu‘, ‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘}
14 >>> info.setdefault(‘stu1105‘,‘SDASGA‘)
15 ‘SDASGA‘
16 >>> info
17 {‘stu1101‘: ‘TengLan Wu‘, ‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘, ‘stu1105‘: ‘SDASGA‘}
18 
19 #update
20 >>> info
21 {‘stu1101‘: ‘TengLan Wu‘, ‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘, ‘stu1105‘: ‘SDASGA‘}
22 >>> b = {
23 ...     ‘stu1101‘:‘Alex Li‘,
24 ...     1:3,
25 ...     2:5
26 ... }
27 >>> info.update(b)
28 >>> info
29 {‘stu1101‘: ‘Alex Li‘, ‘stu1102‘: ‘LongZe Luola‘, ‘stu1103‘: ‘XiaoZe Maliya‘, ‘stu1105‘: ‘SDASGA‘, 1: 3, 2: 5}
30 
31 #items
32 >>> info.items()
33 dict_items([(‘stu1101‘, ‘Alex Li‘), (‘stu1102‘, ‘LongZe Luola‘), (‘stu1103‘, ‘XiaoZe Maliya‘), (‘stu1105‘, ‘SDASGA‘), (1, 3), (2, 5)])
34 
35 #初始化一个字典
36 >>> c = dict.fromkeys([1,2,3],[1,{‘name‘:‘Xmy‘},444]) 
37 >>> c
38 {1: [1, {‘name‘: ‘Xmy‘}, 444], 2: [1, {‘name‘: ‘Xmy‘}, 444], 3: [1, {‘name‘: ‘Xmy‘}, 444]}

View Code

循环dict

1 #method_1
2 for i in info: # 更高效
3     print(i,info[i])
4 
5 #method_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)