Python Dictionary Dict

First, dictionary (dict)1. Dictionaries

Dictionary: denoted by {}, the key value is unique to data {Key:value}.

Key: All must be hashed, immutable data types can be used as key values in the dictionary without any restrictions.

2. Search and delete of dictionaries

1 increase

dic[Key Name] = Value Added, Force add

Dic.setdefault (Key,value) If there is no action in the dictionary, add it if it does not exist.

1DIC = {"K1":"v1","K2":"v2","K3":"v3"}2dic["K4"] ="V4"3Dic.setdefault ("K5","V5")

2. Delete

Dic.pop (key) is deleted by key and the return value is the deleted value

Del Dic[key] deleted via key

Clear () Empty dictionary

Popitem () random deletion (python3.6 is the deletion of the last one, python3.5 is randomly deleted)

1DIC = {"K1":"v1","K2":"v2","K3":"v3"}2Dic.pop ("K1")3 deldic["K2"]4Dic.popitem ()

3. Modifications

Dic[key] = value forced modification

Dic.update (dict) Update/upgrade

1DIC = {"K1":"v1","K2":"v2","K3":"v3"}2Dic1 = {"Q1":"W1","Q2":"W2","Q3":"W3"}3dic["K1"] ="B1"4Dic.update (DIC1)

4. Find

The For loop defaults to getting the keys in the dictionary

Dic[key] View 1: Error When you don't have this key

Dic.get (key, return value) View 2: None returns none, specifying what to return

Dic.setdefault (Key) View 3: No then return none

1DIC = {"K1":"v1","K2":"v2","K3":"v3"}2  forIinchDIC:3     Print. IO4 Print(dic["K1"])5 Print(Dic.get ("K2"))6 Print(Dic.setdefault ("K3"))

3. Other operations of the dictionary:

Keys gets to all the keys that exist in a high-imitated list

Values gets to all the values that exist in a high-imitated list

Items gets to all the key values in the form of a meta-ancestor exist in a highly imitated list

1DIC = {"K1":"v1","K2":"v2","K3":"v3"}2  forIinchDic.keys ():3     Print(i)4  forIinchdic.values ():5     Print(i)6  forIinchDic.items ():7     Print(i)

Deconstruction:

A, B = 1, 2

A, B = (up to)

b = [+]

1DIC = {"K1":"v1","K2":"v2","K3":"v3"}2  forA, binchDic.items ():3     Print(a)4     Print(b)

4. Nesting of dictionaries

DIC = {Key1:value1,key2:value2,{key3:value3,key4:value4}}

1DIC = {'name':'Xiao Ming',' Age': 15,'Family':{2                     'name':' Daming',3                     ' Age': 39,4                     'Salary': 1000005                 },6                 'friend':[7{'name':'Big Bear',' Age': 16},8{'name':'Kumaji',' Age': 14},9                 ]Ten             } One Print(dic['friend'][1]['name'])

Python Dictionary Dict