python:字典
# 容器的通用操作# 1、判断元素是否在容器中:元素 in 容器# 2、获取容器长度:len(容器)# 3、遍历容器:for x in 容器#字典key值重复,后面会覆盖前面的dict_one={"key1":"value1","key2":"value2","key3":3,"key4":4}dict_two=dict(kk1="vv1",kk2="vv2",kk3=3)# 一、判断key,是否在字典中print("++++++判断key,是否在字典中++++++")flag1="key1"indict_oneprint(f"key1是否在字典中:{flag1}")flag2="kkk"indict_twoprint(f"kkk是否在字典中:{flag2}")# 结果:# key1是否在字典中:True# kkk是否在字典中:False# 二、遍历print("++++++遍历++++++")# 方式一:只遍历key值print("方式一:只遍历key值")foritemindict_one:print(item)# 结果:# key1# key2# key3# key4# 方式二:遍历value值print("方式二:遍历value值")forvalueindict_one.values():print(value)# 结果:# value1# value2# 3# 4# 方式三:遍历字典对象:key,valueprint("方式三:遍历字典对象:key,value")forkey,valueindict_two.items():print(f"key为:{key}-> value为:{value}")# 结果:# key为:kk1 -> value为:vv1# key为:kk2 -> value为:vv2# key为:kk3 -> value为:3# 三、添加\修改print("++++++添加\修改++++++")dict_three={"name":"zhangsan","sex":"1"}print(f"添加前:{dict_three=}")dict_three["age"]=20#key值存在修改,不存在添加dict_three["sex"]="2"#key值存在修改,不存在添加print(f"添加后:{dict_three=}")# 结果:# 添加前:dict_three={'name': 'zhangsan', 'sex': '1'}# 添加后:dict_three={'name': 'zhangsan', 'sex': '2', 'age': 20}dict_three2={"name":"zhangsan2","sex":"100"}#key值存在修改,不存在添加dict_three2.update({"name":"改成汉字张三","add":"updateadd"})print(f"{dict_three2=}")# 结果: dict_three2={'name': '改成汉字张三', 'sex': '100', 'add': 'updateadd'}# 四、删除print("++++++删除++++++")dict_four=dict(name='李四',sex=0,age=18)print(f"删除前:{dict_four=}")dict_four.pop("name")#删除key存在的字典#dict_four.pop("aaaa") #删除key不存在的字典,会报错print(f"删除后:{dict_four=}")deldict_four["age"]#del删除元素print(f"del删除后:{dict_four=}")# 结果:# 删除前:dict_four={'name': '李四', 'sex': 0, 'age': 18}# 删除后:dict_four={'sex': 0, 'age': 18}# del删除后:dict_four={'sex': 0}# 五、查print("++++++查++++++")dict_five={"aa":"bb","aaaa":"bbbb"}print(f"字典查找:{dict_five["aaaa"]}")# 结果: 字典查找:bbbb# 六、字典推导式print("++++++字典推导式++++++")nums=range(97,100)chrs=['a','b','c','d']dict_six={key:valueforkeyinnumsforvalueinchrsifkey==ord(value)}#ord方法字符转数字print(f"字典推导式生成的字典:{dict_six=}")# 结果: 字典推导式生成的字典:dict_six={97: 'a', 98: 'b', 99: 'c'}结果:
++++++判断key,是否在字典中++++++
key1是否在字典中:True
kkk是否在字典中:False
++++++遍历++++++
方式一:只遍历key值
key1
key2
key3
key4
方式二:遍历value值
value1
value2
3
4
方式三:遍历字典对象:key,value
key为:kk1 -> value为:vv1
key为:kk2 -> value为:vv2
key为:kk3 -> value为:3
++++++添加\修改++++++
添加前:dict_three={‘name’: ‘zhangsan’, ‘sex’: ‘1’}
添加后:dict_three={‘name’: ‘zhangsan’, ‘sex’: ‘2’, ‘age’: 20}
dict_three2={‘name’: ‘改成汉字张三’, ‘sex’: ‘100’, ‘add’: ‘updateadd’}
++++++删除++++++
删除前:dict_four={‘name’: ‘李四’, ‘sex’: 0, ‘age’: 18}
删除后:dict_four={‘sex’: 0, ‘age’: 18}
del删除后:dict_four={‘sex’: 0}
++++++查++++++
字典查找:bbbb
++++++字典推导式++++++
字典推导式生成的字典:dict_six={97: ‘a’, 98: ‘b’, 99: ‘c’}