python中字典排序，字典列表排序

import operator

字典排序

1. 按字典值排序（默认为升序）

x = {1:2, 3:4, 4:3, 2:1, 0:0}   
1. sorted_x = sorted(x.iteritems(), key=operator.itemgetter(1))  
print sorted_x  
[(0, 0), (2, 1), (1, 2), (4, 3), (3, 4)]  
如果要降序排序,可以指定reverse=True  
2. sorted_x = sorted(x.iteritems(), key=operator.itemgetter(1), reverse=True)  
print sorted_x  
[(3, 4), (4, 3), (1, 2), (2, 1), (0, 0)]  

2. 或者直接使用list的reverse方法将sorted_x顺序反转

sorted_x.reverse()  

3. 更为常用的方法是,用lambda表达式

3. sorted_x = sorted(x.iteritems(), key=lambda x : x[1])  
print sorted_x  
  [(0, 0), (2, 1), (1, 2), (4, 3), (3, 4)]  

4. sorted_x = sorted(x.iteritems(), key=lambda x : x[1], reverse=True)  
print sorted_x  
[(3, 4), (4, 3), (1, 2), (2, 1), (0, 0)]  

包含字典dict的列表list的排序方法与dict的排序类似,如下：

x = [{'name':'Homer', 'age':39}, {'name':'Bart', 'age':10}]  
sorted_x = sorted(x, key=operator.itemgetter('name'))  
print sorted_x  
[{'age': 10, 'name': 'Bart'}, {'age': 39, 'name': 'Homer'}]  

sorted_x = sorted(x, key=operator.itemgetter('name'), reverse=True)  
print sorted_x  
[{'age': 39, 'name': 'Homer'}, {'age': 10, 'name': 'Bart'}]  

sorted_x = sorted(x, key=lambda x : x['name'])  
print sorted_x  
[{'age': 10, 'name': 'Bart'}, {'age': 39, 'name': 'Homer'}]  

5. sorted_x = sorted(x, key=lambda x : x['name'], reverse=True)  
print sorted_x  
[{'age': 39, 'name': 'Homer'}, {'age': 10, 'name': 'Bart'}]