Python dictionary keys() usage and example

Python dictionary methods

keys() method returns a view object that displays a list of all keys in the dictionary

The syntax of keys() is:

dict.keys()

keys() parameters

keys() does not accept any parameters.

keys() return value

keys() returns a view object that displays a list of all keys.

After changing the dictionary, the view object will also change accordingly.

Example1：How does keys() work?

person = {'name': 'Phill', 'age':　22, 'salary':　3500.0}
print(person.keys())
empty_dict = {}
print(empty_dict.keys())

When running the program, the output is:

dict_keys(['name', 'salary', 'age'])
dict_keys([])

Example2：How does keys() work when updating a dictionary?

person = {'name': 'Phill', 'age':　22,}
print('Before the dictionary is updated')
keys = person.keys()
print(keys)
# Add an element to the dictionary
person.update({'salary':　3500.0)
print('\nAfter the dictionary is updated')
print(keys)

When running the program, the output is:

Before the dictionary is updated
dict_keys(['name', 'age'])
After the dictionary is updated
dict_keys(['name', 'age', 'salary'])

Here, when the dictionary is updated, the keys will also be automatically updated to reflect the changes.

Python dictionary methods