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:\n")
od = OrderedDict()
od['a'] = 1
od['b'] = 2
od['c'] = 3
od['d'] = 4

for key, value in od.items():
    print(key, value) 

print("\nAfter deleting:\n")
od.pop('c')
for key, value in od.items():
    print(key, value) 

print("\nAfter re-inserting:\n")
od['c'] = 3
for key, value in od.items():
    print(key, value)