Python字典按值排序、包含字典的列表按字典值排序的方法

#-*- encoding=utf-8 -*-

import operator

#按字典值排序（默认为升序）

x = {1:2, 3:4, 4:3, 2:1, 0:0}

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

sorted_x = sorted(x.iteritems(), key=operator.itemgetter(1), reverse=True)

print sorted_x

#[(3, 4), (4, 3), (1, 2), (2, 1), (0, 0)]

#或者直接使用list的reverse方法将sorted_x顺序反转

#sorted_x.reverse()

#取代方法是,用lambda表达式

sorted_x = sorted(x.iteritems(), key=lambda x : x[1])

print sorted_x

#[(0, 0), (2, 1), (1, 2), (4, 3), (3, 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‘}]

sorted_x = sorted(x, key=lambda x : x[‘name‘], reverse=True)

print sorted_x

#[{‘age‘: 39, ‘name‘: ‘Homer‘}, {‘age‘: 10, ‘name‘: ‘Bart‘}]