Python learning 2: detailed dictionary basics

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 作者：NiceCui 
 <ul> 
 <li>本文谢绝转载，如需转载需征得作者本人同意，谢谢。</li> 
 <li>本文链接：http://www.cnblogs.com/NiceCui/p/7862377.html</li> 
 <li>邮箱：[email protected]</li> 
 <li>日期：2017-11-19</li> 
 </ul> 
 PYTHON 学习二：词典基础详解 
 （学习不要求多，小计划能学会体验到乐趣便可） 
 一：介绍 
 PYTHON 词典其实和 JAVA The HashMap is very similar, both are implemented by Hash table, all are The key-value pair is stored, that is, the dictionary is an array, and the index of the array is the hash of the key obtained after the function is processed. In fact, you will encounter many similar storage methods in the learning of programming languages. For example, the cache system Memcached stores data in key-value pairs, and Redis also has them. Therefore, the key-value pair storage method is widely used in programming languages. 
 ;A dictionary is a container that can hold multiple elements, but the worddictionary is not position-indexed, Dictionary allows a custom way to index data. 

 Dictionaries can contain multiple elements, each of which is easy to divide; 
 ;The element of the dictionary consists of two parts: key(Key) and value(Value), the key is the index of the data, the value is the data itself, and the key and value are in one-to-one correspondence. 
   
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 2 #coding:utf-8
 3 '''
 4 Created on 2017-11-19
 5 @author: NiceCui
 6 '''
 7 
 8 example_dict = {"a":1,"b":2,"c":3}
 9 
10 print(type(example_dict)) #输出 <type 'dict'>
11 
12 print(example_dict["a"]) #输出 1
13 
14 print(example_dict["b"]) #输出 2
15 
16 print(example_dict["c"]) #输出 3</pre> 
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 Third: Modify or increase the value of an element in the dictionary 

 <pre> 1 #!/usr/bin/ PYTHON 
 2 #coding:utf-8
 3 '''
 4 Created on 2017-11-19
 5 @author: NiceCui
 6 '''
 7 
 8 example_dict = {"a":1,"b":2,"c":3}
 9 
10 example_dict["a"] = 10 #修改键 "a" 的值为 10
11 
12 example_dict["b"] = 20 #修改键 "b" 的值为 20
13 
14 example_dict["d"] = 4 #增加键是 "d" 值是 4
15 
16 print(example_dict) #输出：{'a': 10, 'c': 3, 'b': 20, 'd': 4}</pre> 
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 构建一个新的空词典 
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 <pre>#!/usr/bin/ PYTHON 
#coding:utf-8
'''
Created on 2017-11-19
@author: NiceCui
'''
 

 <pre>1 #!/usr/bin/ PYTHON 
2 #coding:utf-8
3 '''
4 Created on 2017-11-19
5 @author: NiceCui
6 '''
7 
8 
9 example_dict ={"premium":0.2,"tax":0.15}</pre> 
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In the dictionary example, and in most application scenarios, we use strings as dictionary keys. But other types of data, such as arrays and boolean values, can also be used as keys for dictionaries, easy to learn, play to learn, and learn to be happy.  

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Python learning 2: detailed dictionary basics

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