Python Dictionary update() Method: Add and Replace Items

my_dict.update(other) adds key-value pairs to an existing dictionary and replaces the values of keys that already exist. The method changes the dictionary in place and returns None.

See the complete Dictionary Methods table for the other dictionary operations in this cluster.

my_dict={'a':'One','b':'Two','c':'Three'}
my_dict2={'d':'Four'} # new key 
my_dict.update(my_dict2)
print(my_dict)

Output is here

{'a': 'One', 'b': 'Two', 'c': 'Three', 'd': 'Four'}

If input key available then value is updated.

my_dict={'a':'One','b':'Two','c':'Three'}
my_dict2={'b':'New value'} # existing key 
my_dict.update(my_dict2)
print(my_dict)

Output (key b with New value is updated )

{'a': 'One', 'b': 'New value', 'c': 'Three'}

Adding new keys with values

my_dict={'a':'One','b':'Two','c':'Three'}
my_dict.update(d='Four',e='Five')
print(my_dict)

Output

{'a': 'One', 'b': 'Two', 'c': 'Three', 'd': 'Four', 'e': 'Five'}

Adding and updating values

We can add new key with values and update existing values by using update()

my_dict={'a':'One','b':'Two','c':'Three'}
my_dict.update(b='New one',d='Four',e='Five')
print(my_dict)

Output ( value of key b is updated and new keys d and e added )

{'a': 'One', 'b': 'New one ', 'c': 'Three', 'd': 'Four', 'e': 'Five'}

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