Python---Dictionary

#字典是key-value data type, the dictionary is unordered, there is no subscript (the list has subscript), key must be unique

info = {     "stu001": "Fengxiaoli",     "stu002": "CX",      "stu003": "Wyc",     "stu004": "Ljh",}###-----------------Cycle dictionary For i  in info:               #推荐使用     print (I,info[i]) for k,v in info.items ():     #不推荐, Because it is first converted to a list in print, the data amount of time is very slow     print (K,V)         ### -----------------Query Print ("stu001"  in info)       #判断key是否在字典中, same as Py2   Info.has_key ("stu001") Print (Info.get ("stu002"))     #通过key获取value, print (info["stu001") is recommended for print ( Info)           ###-----------------Modify info["stu003"] =   "Fzl"          #有那个key就修改, no new info["stu005"] =  "Fzl" Print (Info) # # #-----------------Delete del info                         #删除整个字典del  info["stu005"]info.pop ("stu004") Info.popitem ()                   #随机删除一组 # # #-----------------Merge two dictionaries b = {     "stu001": "FXL",     3:5,     4:8,}info.update (b)        #合并字典info和字典b, with duplicate updates, Do not repeat the merge print (info) # # #-----------------Turn the dictionary into List print (Info.items ()) # # #-----------------Initialize a dictionary c =  Dict.fromkeys ([7,8,9], "test") print (c) #输出 {8:  ' test ', 9:  ' test ', 7:  ' test '}c1 =  dict.fromkeys ([7,8,9],{1: "Feng", 2: "CX", 3: "FXL"}) print (c1) #输出 {8: {1:  ' Feng ', 2:  ' CX ',  3:  ' fxl '}, 9: {1:  ' Feng ', 2:  ' cx ', 3:  ' FXL '}, 7: {1:   ' Feng ', 2:  ' cx ', &NBsp;3:  ' FXL '}}c1[8][2]= "xia"        #类似浅copy, the data in the two-level dictionary points to the same memory address, modifying one all changes print (c1 ) #输出 {8: {1:  ' Feng ', 2:  ' xia ', 3:  ' fxl '}, 9: {1:  ' Feng ',  2:   ' xia ', 3:  ' fxl '}, 7: {1:  ' Feng ', 2:  ' xia ', 3:  ' FXL '}}       ###-----------------Multi-level dictionary info2 = {     "stu001": {" FXL ": [" Gender: Male "," Age: + "]},    " stu002 ": {" CX ": [" Gender: Female "," Age: "]},    " Stu003 ": {" Fzl ": [" Gender: Male "," Age: "]},}info2[" stu001 "] [FXL"][1] =  "Age:               #修改info2. SetDefault ("stu004", {"Ljh": ["Gender: Female", "Age: +]})        #增加, if this key in the dictionary does not change the original value, no new print (Info2)

Python---Dictionary