在新旧字典中，新旧字典均存在的KEY进行更新。旧字典存在而新字典不存在，则删除。旧字典不存在而新字典存在的KEY，则新增；
old_dict = {
"#1": {‘hostname‘: ‘c1‘, ‘cpu_count‘: 2, ‘mem_capicity‘: 80},
"#2": {‘hostname‘: ‘c1‘, ‘cpu_count‘: 2, ‘mem_capicity‘: 80},
"#3": {‘hostname‘: ‘c1‘, ‘cpu_count‘: 2, ‘mem_capicity‘: 80}
}
new_dict = {
"#1": {‘hostname‘: ‘c1‘, ‘cpu_count‘: 2, ‘mem_capicity‘: 80},
"#3": {‘hostname‘: ‘c1‘, ‘cpu_count‘: 2, ‘mem_capicity‘: 80},
"#4": {‘hostname‘: ‘c1‘, ‘cpu_count‘: 2, ‘mem_capicity‘: 80}
}
# 转换成set集合
old = set(old_dict)
new = set(new_dict)
# 交集
update_set = new.intersection(old)
# 差集
delete_set = old.symmetric_difference(update_set)
# 差集
add_set = new.symmetric_difference(update_set)
print update_set
print delete_set
print add_set
原文：http://www.cnblogs.com/mjoy/p/5773466.html