python OrderedDict

15年16年接触python时候，还不知道这个函数，只知道dict的无序，造成了一些麻烦

今天view 代码，发现了 OrderedDict()

在python2.7中比较吃内存

pop(获取指定key的value，并在字典中删除)

from collections import OrderedDict 
  
print("Before deleting:
") 
od = OrderedDict() 
od['a'] = 1
od['b'] = 2
od['c'] = 3
od['d'] = 4
  
for key, value in od.items(): 
    print(key, value) 
  
print("
After deleting:
") 
od.pop('c') 
for key, value in od.items(): 
    print(key, value) 
  
print("
After re-inserting:
") 
od['c'] = 3
for key, value in od.items(): 
    print(key, value)