How to use dictionary in python, common methods of python dictionary

Hello everyone, the editor is here to answer the following questions for you, how to use dictionaries in python, and common methods of python dictionaries. Let us take a look today!

1. Create a dictionary

Description: Generate dictionary

grammar:

dic={
     
     'k1':'v1'}

Example:

dic=dict(k1='v1',k2='v2')

dic={
      
      'k1':'v1','k2':'v2'}

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2. Get the key value get

Description: Get the key value. If there is no key in the dictionary, output the custom field. The default is none.

grammar:

    def get(self, k, d=None): # real signature unknown; restored from __doc__
        """ D.get(k[,d]) -> D[k] if k in D, else d.  d defaults to None. """
        pass

Example:

dic={
       ' k1 ' : ' v1 ' , ' k2 ' : ' v2 ' } 
a =dic.get( ' k1 ' ) 
v1 
c =dic.get( ' k3 ' ) 
none     #There is no such key in the dictionary, and none is displayed 
c=dic.get( ' k3 ' , ' no ' )   
no    #There is no such key in the dictionary, and no is displayed
      

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3. Get the value of the key

Description: Get the key in the dictionary

grammar:

 def keys(self): # real signature unknown; restored from __doc__
        """ D.keys() -> a set-like object providing a view on D's keys """
        pass

Example:

dic=dict(k1= ' v1 ' ,k2= ' v2 ' ) 
dic.keys() 
for k in dic.keys():
     print (k) 

result: k1, k2   #Display the result

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4. Get key value

Description: Get the key value in the dictionary

grammar:

   def values(self): # real signature unknown; restored from __doc__
        """ D.values() -> an object providing a view on D's values """
        pass

Example:

dic=dict(k1='v1',k2='v2')
for v in dic.values():
    print(v)

v=v1,v2 #结果

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5. Get the value of the key-value pair　　

Description: Get the key-value pairs in the dictionary

grammar:

    def items(self): # real signature unknown; restored from __doc__
        """ D.items() -> a set-like object providing a view on D's items """
        pass

Example:

dic={
      
      'k1':'v1','k2':'v2'}

for k,v in dic.items():
    print(k,v)

#结果
k1 v1
k2 v2   

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6. Delete key-value pairs　　

Description: Delete a key in a dictionary

grammar:

 def pop(self, k, d=None): # real signature unknown; restored from __doc__
        """
        D.pop(k[,d]) -> v, remove specified key and return the corresponding value.
        If key is not found, d is returned if given, otherwise KeyError is raised
        """
        pass

Example:

dic=dict(k1='v1',k2='v2',k3='v3')
dic.pop('k2')
print(dic)

dic={
      
      'k3': 'v3', 'k1': 'v1'}  #结果

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7. Update key-value pairs　　

Description: Update keys in the dictionary

grammar:

   def update(self, E=None, **F): # known special case of dict.update
        """
        D.update([E, ]**F) -> None.  Update D from dict/iterable E and F.
        If E is present and has a .keys() method, then does:  for k in E: D[k] = E[k]
        If E is present and lacks a .keys() method, then does:  for k, v in E: D[k] = v
        In either case, this is followed by: for k in F:  D[k] = F[k]
        """
        pass

Example:

dic=dict(k1='v1',k2='v2',k3='v3')
dic.update({
       
       'k4':'v4'})
print(dic)

dic={
      'k4': 'v4', 'k3': 'v3', 'k1': 'v1', 'k2':v2'
      ' } #result _

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8. Update key value　　

Description: Update keys in the dictionary

grammar:

dict[key]=value　　

Example:

dic=dict(k1='v1',k2='v2',k3='v3')
dic['k1']=1
print(dic)

dic={
      
      'k3': 'v3', 'k1': 1, 'k2': 'v2'}  #结果

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Reprinted at: https://www.cnblogs.com/xujianghua/p/6399312.html