Dictionary operations and dictionary functions in python

The dictionary

dict_fruit = {'apple':' apple ','banana':' banana ','cherry':' cherry ','avocado':' avocado ','watermelon':' watermelon '} 

Dictionary operation

# The way a dictionary is traversed  
# The default traversal ( traverse key) 
for value in dict_fruit: 
  print(value) 
''''' 
 The value of the traversal : 
watermelon 
apple 
cherry 
avocado 
banana 
''' 
# use key traverse ( With default traversal 1 sample ) 
for key in dict_fruit.keys(): 
  print(key) 
''''' 
 The value of the traversal : 
watermelon 
apple 
cherry 
avocado 
banana 
''' 
# use value traverse  
for value in dict_fruit.values(): 
  print(value) 
''''' 
 The value of the traversal : 
 apple  
 avocado  
 banana  
 watermelon  
 cherry  
''' 
# use key,value traverse  
for key,value in dict_fruit.items(): 
  print(key+'--->'+value) 
''''' 
 The value of the traversal : 
avocado---> avocado  
apple---> apple  
banana---> banana  
cherry---> cherry  
watermelon---> watermelon  
''' 
# Create a dictionary  
# use dict() 
res = dict(brand = ' brand ',size=' size ',color=' color ') 
print(res,type(res)) 
''''' 
res The results of : 
{'size': ' size ', 'brand': ' brand ', 'color': ' color '} <class 'dict'> 
''' 
# use zip() and dict() 
keys = ['1','2','3','4','5'] 
values = [1,2,3,4,5] 
res = dict(zip(keys,values)) 
print(res,type(res)) 
''''' 
res The results of : 
{'3': 3, '4': 4, '1': 1, '2': 2, '5': 5} <class 'dict'> 
''' 
# The derivation of the dictionary  
res = {k+' The Chinese is '+v for k,v in dict_fruit.items()} 
print(res) 
''''' 
res The results of : 
{'watermelon Chinese is watermelon ', 'avocado It's avocado in Chinese ', 'banana The Chinese is banana ', 'cherry Chinese is cherry ', 'apple The Chinese is apple '} 
''' 

Dictionary function

# Empty dictionary  
test1 = {1:'1'} 
test1.clear() 
print(test1) 
''''' 
test1 The results of : 
{} 
''' 
# Copy a dictionary ( Copied into 1 A new dictionary ) 
test2 = {2:'2'} 
test2_copy = test2.copy() 
print(test2_copy) 
''''' 
test2 The results of : 
{2: '2'} 
''' 
# Use the specified key and value making 1 A dictionary  
list_test = ['a','b','c'] 
test3 = {}.fromkeys(list_test,'ojbk') 
print(test3) 
''''' 
test3 The results of : 
{'a': 'ojbk', 'b': 'ojbk', 'c': 'ojbk'} 
''' 
# will 1 The number of dictionaries is converted to 2 Level of container ( The middle container ) 
res = dict_fruit.items() 
print(res,type(res)) 
''''' 
res The results of : 
dict_items([('avocado', ' avocado '), ('apple', ' apple '), ('banana', ' banana '), ('watermelon', ' watermelon '), ('cherry', ' cherry ')]) <class 'dict_items'> 
''' 
# The dictionary key Make up a new container  
res = dict_fruit.keys() 
print(res,type(res)) 
''''' 
res The results of : 
dict_keys(['watermelon', 'cherry', 'avocado', 'apple', 'banana']) <class 'dict_keys'> 
''' 
# The dictionary value Make up a new container  
res = dict_fruit.values() 
print(res,type(res)) 
''''' 
res The results of : 
dict_values([' avocado ', ' banana ', ' cherry ', ' apple ', ' watermelon ']) <class 'dict_values'> 
''' 
# According to the key Delete the data in the dictionary  
test4 = {1:'1',2:'2',3:'3'} 
test4.pop(2) 
print(test4) 
''''' 
test4 The results of : 
{1: '1', 3: '3'} 
''' 
# In turn, the pop-up ( delete ) Dictionary data  
test5 = {1:'1',2:'2',3:'3',4:'4',5:'5'} 
test5.popitem() 
print(test5) 
test5.popitem() 
print(test5) 
test5.popitem() 
print(test5) 
''''' 
test5 The results in turn : 
{2: '2', 3: '3', 4: '4', 5: '5'} 
{3: '3', 4: '4', 5: '5'} 
{4: '4', 5: '5'} 
''' 
# update dict The data in the ( update 1 One that doesn't exist key when , Can be used to add new data ) 
test6 = {'super':'Eric','ssuper':'Cbabe','sssuper':'Gogo','supreme':'wiz333'} 
# Update the data  
test6.update(super='Eric-LPL') 
print(test6) 
# Add data  
test6.update(niceboy='Bigmao') 
print(test6) 
''''' 
test6 The results in turn : 
{'ssuper': 'Cbabe', 'supreme': 'wiz333', 'sssuper': 'Gogo', 'super': 'Eric-LPL'} 
{'ssuper': 'Cbabe', 'supreme': 'wiz333', 'niceboy': 'Bigmao', 'sssuper': 'Gogo', 'super': 'Eric-LPL'} 
''' 
# To obtain dict The data in the ( use key To obtain ) 
test7 = {1:'1',2:'2',3:'3',4:'4',5:'5'} 
res = test7.get(1) 
print(res,type(res)) 
''''' 
test7 The results of : 
1 <class 'str'> 
''' 
# to dict Add data (setdefault, Cannot be used to update data ) 
test8 = {1:'1',2:'2',3:'3',4:'4',5:'5'} 
test8.setdefault(6,'6') 
print(test8) 
''''' 
test8 The results of : 
{1: '1', 2: '2', 3: '3', 4: '4', 5: '5', 6: '6'} 
''' 

conclusion