最近学习了字典,笔记整理在代码段中。
# _author:VULCAN
# date:2018/8/14
# 字典
# 增加:
dic = {"8": "3306", "name": "p", "kl": "xzc"}
# print(dic)
#
# dic["8"] = "4212" # 若键存在,将替换键对应的原来的key,若键不存在,将新增一对键值对
# print(dic)
#
# dic["sex"] = "male"
# print(dic)
# # 键存在,不改动,返回字典中相应的建对应的相应的值
# return1 = dic.setdefault("name", "9910")
# print(return1)
# # 键不存在,在字典中增加新的键值对,并返回相应的值
# return2 = dic.setdefault("height", 186)
# print(return2)
# 删除:
# dic.clear() # 清除字典
# print(dic)
# dic.pop("8") # 删除字典中指定键值对,并返回一个该键值对的值
# ret = dic.pop("8") # 跟列表pop删除操作一样,有返回值
# print(ret)
# ret1 = dic.popitem() # 随机删除某组键值对,并以元组的方式返回
# print(ret1)
# print(dic)
# print(dic)
# a = dic.copy() # 拷贝一个跟dic数据一致的字典
# print(a)
# del dic["8"] # 删除字典中指定键值对
# print(dic)
# del dic # 删除整个字典
# print(dic)
# 修改:
# dic["name"] = "fok"
# print(dic)
# dic1 = {1: 3, 2: 5, 5: 6}
# dic1.update(dic)
# print(dic1)
# print(dic)
# dic2 = {1: "opg", 9: '"lm'} # 覆盖时没有相同的键时,直接添加到dic1中,有相同的键是,将values值替换
# dic1.update(dic2)
# print(dic1)
# print(dic2)
# # 查找:通过键来查找值
# print(dic["name"])
# print(dic.keys())
# print(dic.values())
# print(dic.items())
# print(type(dic.values()))
# # 将查到的值转换为列表
# print(list(dic.keys()))
# print(list(dic.values()))
# print(list(dic.items()))
# 这样也可以生成字典,通过dict.fromkeys()方法,将["test1", "test2", "test3"]中的值当做每一对键值对的键,["valuestest"]当做所有键值对的值
# dic_test = dict.fromkeys(["test1", "test2", "test3"], ["valuestest"])
# print(dic_test) # {'test1': ['valuestest'], 'test2': ['valuestest'], 'test3': ['valuestest']}
# 字典嵌套使用:
# dic_1 = {"1001": {"101": ["101_01", "101_02"], "201": ["201_01", "201_02"]},
# "1002": {"102": ["102_02", "102_02"], "202": ["202_01", "202_02"]},
# "1003": {"103": ["103_03", "103_03"], "203": ["203_01", "203_02"]}}
# print(dic_1)
# dic_1["1002"]["202"][1] = "3306"
# print(dic_1)
# 字典的排序
dic_2 = {333: "777", 666: "000", 111: "999"}
# print(sorted(dic_2)) # 默认是对键进行排序
# print(sorted(dic_2.keys())) # 效果同上
# print(sorted(dic_2.values())) # 对值进行排序
# 遍历字典:
# for i in dic_2: # 效率高
# print(i, dic_2[i])
#
# for i, v in dic_2.items(): # 效率较上低
# print(i, v)
# 字符串String操作:
# "Hello"跟'Hello'没有任何区别
# a = "les's go!"
# print(a)
# a = "'他''她''它'"
# print(a)
# print("hello" * 100) # print("hello"*n) n为几就打印几遍"Hello"