dictionaries and their operations
The dictionary is used to store the two corresponding keys and values, that is, the dict type; When a dictionary is created, each key is used to get the corresponding value, and the key in the dictionary cannot be duplicated; it is characterized by a Key-value key value type, unordered, and no subscript can be found by subscript.
(1) Dictionary replacement, add, delete, find
infor={ ‘2014132001‘:"DiaoCan", ‘2014132002‘:"DaQiao", ‘2014132003‘:"HuanhYueYing"}print(infor)infor[‘2014132002‘]=‘XiaoQiao‘ # 替换print(infor)infor[‘2014132089‘]=‘wuzhetain‘ # 添加print(infor)# del infor[‘2014132089‘] # 删除#infor.popitem() # 随机删除infor.pop (‘2014132089‘)print(infor)print(infor[‘2014132001‘]) # 查找print(infor.get(‘2014132001‘) ) # 更为安全的查找,当键不存在的时候不会报错print(‘2014132001‘ in infor) # 查某是否存在,返回的是布尔类型
(2) Updating of dictionaries
infor={ ‘2014132001‘:"DiaoCan", ‘2014132002‘:"DaQiao", ‘2014132003‘:"HuanhYueYing"}print(infor)a={ ‘2014132001‘:‘LuBu‘, ‘2014132004‘:‘Guanyu‘, ‘2014132005‘:‘Dongzhuo‘}infor.update(a) # 有的就更新,没有的就添加print(infor)
(3) Conversion and extension of dictionaries
infor={ ‘2014132001‘:"DiaoCan", ‘2014132002‘:"DaQiao", ‘2014132003‘:"HuanhYueYing"}print(infor)print(infor.items() ) # 将字典转化为列表b=dict.fromkeys([1,2,3,4],[1,{‘name‘:‘zhangfei‘},‘Zhaoyun‘]) # 这里要注意的就是1,2,3,4所对应的值是同一个print(b)b[2][1][‘name‘]=‘Xiahoudun‘print(b)
(4) Output of the dictionary
infor={ ‘2014132001‘:"DiaoCan", ‘2014132002‘:"DaQiao", ‘2014132003‘:"HuanhYueYing"}print(infor)for i in infor: # 建议使用这个 print(i,infor[i])for k,v in infor.items(): # 多了一步转换为列表 print(k,v)
(5) Multilevel specified nesting
Site_of_world={ ‘American‘:{ ‘www.barrett.net‘:["Barrett Firearms Manufacturing","巴雷特×××公司"], ‘sands.com‘:["Las Vegas Sands","拉斯×××金沙集团 "], ‘www.omnicomgroup.com‘:["Omnicom Group","奥米康集团"], ‘www.wyethnutrition.com.hk ‘:["Wyeth","惠氏"] } , ‘Japan‘:{ ‘www.unicharm.com.cn‘:["Unicharm Group","尤妮佳集团"], ‘www.klab.com/cn‘:["KLab","可来"] } , ‘Chain‘:{ ‘hknd-group.com/cn/‘:["HKND Group","HKND集团"], ‘www.eegmusic.com‘:["Emperor Entertainment","英皇娱乐"] }}print(Site_of_world.keys())print(Site_of_world.values())print(Site_of_world)Site_of_world.setdefault(‘Chain‘,{‘www.baidu.com‘:"百度 "}) # 键存在的情况下,不改变value的值print(Site_of_world)Site_of_world.setdefault(‘South Korea‘,{‘www.smtown.com‘:"SM娱乐"}) # 键不存在的情况下,创建新的key-valueprint(Site_of_world)
Learning notes for Python/002-5 (2018-5-21)