"Python3" dictionary

The dictionary is the Key-value data type

Create

info = {    ' stu01 ': ' Jack ',    ' stu02 ': ' Mike ',    ' stu03 ': ' Jay '}

Features of the dictionary:

• Dict is disordered.
• Key must be unique and inherently heavy

Increase

>>>info[' stu05 ' = ' kit ' #自动创建 {' stu01 ': ' Jack ', ' stu02 ': ' Mike ', ' stu03 ': ' Jay ', ' stu05 ', ' kit '}

By deleting

>>> Info.pop ("stu03") #标准删除, you must add the parameter {' stu01 ': ' Jack ', ' stu02 ': ' Mike '}

>>> del info[' stu03 ' #通用删除 {' stu01 ': ' Jack ', ' stu02 ': ' Mike '}

>>> Info.popitem () #随机删除 {' stu01 ': ' Jack ', ' stu03 ': ' Jay '}

Change

>>>info[' stu02 ' = ' bob '
{' stu01 ': ' Jack ', ' stu02 ': ' Bob ', ' stu03 ': ' Jay '}

Check

>>> ' stu02 ' in info #标准用法True >>> info.get (' stu02 ')  #获取 ' Mike ' >>> info["stu1105"]  # If a key does not exist, an error, get will not, does not exist only return Nonetraceback (most recent call last):  File "<stdin>", line 1, in <module> Keyerror: ' stu1105 '

Multi-level dictionary nesting and manipulation

City = {'    Asia ': {'        China ': [' Beijing ', ' Shanghai ', ' Guangzhou '],        ' Russia ': [' Moscow ', ' St Petersburg '],        ' Japan ': [' Tokyo ', ' Nagoya ', ' Osaka ']    },    ' Europe ': {        ' uk ': [' London ', ' Birmingham ']    },    ' Oceania ': {        ' Australia ': [' Sydney ', ' Canberra ']    }

city[Asia] [China][2]= ' Shenzhen ' #将广州改成深圳

Other

 #values 
 >>> info.values () 
 [' Jack ', ' Mike ', ' Jay '] 
 
 #keys 
 >>> Info.keys () 
 [' stu01 ', ' stu02 ', ' stu03 '] 
 
 #setdefault #键值存在则罢, non-existent add 
 >>> info.setdefault (' stu06 ' Jane ') 
 {' stu01 ': ' Jack ', ' stu02 ': ' Mike ', ' stu03 ': ' Jay ', ' stu06 ', ' Jane '} 
 >>> Info.setdefault (' Stu02 ', ' Jane ') 
 {' stu01 ': ' Jack ', ' stu02 ': ' Mike ', ' stu03 ': ' Jay '} 
 
 #update #合并字典, overwrite 
 >>> b if key value repeats = {1:2,3:4, ' stu01 ': ' Kit '} 
 >>> info.update (b) 
 {' stu01 ': ' Kit ', ' stu02 ': ' Mike ', ' stu03 ': ' Jay ', 1:2,3:4} 
 
 #items #字典转列表 with Ganso 
 >>>info.items () 
 [(' Stu01 ': ' Jack '), (' stu02 ': ' Mike '), (' stu03 ': ' Jay ')] 
 
 #通过一个列表生成默认dict 
 >>> Dict.fromkeys ([2], ' TESTD ') 
 {1: ' testd ',: ' Testd ', 3: ' TESTD '} 
 >>>c=dict.fromkeys ([1,2,3],[' Jack ', ' Sandra ']) 
 >>>c[2][1]= ' Happy ' #全改了 
 {1:[' Jack ', ' happy '],3:[' Jack ', ' Happy '],3:[' Jack ', ' Happy ']} 

Cycle

#方法1for key in Info:  #高效    print (Key,info[key]) #方法2for key,value in    info.items (): #先把dict转成list, MO When the data is large Print (Key,value)

"Python3" dictionary