The keys() method in Python Dictionary, returns a view object that displays a list of all the keys in the dictionary in order of insertion using Python.
Syntax: dict.keys()
Parameters: There are no parameters.
Returns: A view object is returned that displays all the keys. This view object changes according to the changes in the dictionary.
Method 1: Accessing the key using the keys() method
A simple example to show how the keys() function works in the dictionary.
Python3
Dictionary1 = { 'A' : 'Geeks' , 'B' : 'For' , 'C' : 'Geeks' }
print (Dictionary1.keys())
|
Output:
dict_keys(['A', 'B', 'C'])
Method 2: Python access dictionary by key
Demonstrating the practical application of keys() using the Python loop.
Python3
test_dict = { "geeks" : 7 , "for" : 1 , "geeks" : 2 }
j = 0
for i in test_dict:
if (j = = 1 ):
print ( '2nd key using loop : ' + i)
j = j + 1
|
Output:
2nd key using loop : for
TypeError: 'dict_keys' object does not support indexing
Time Complexity: O(n)
Auxiliary Space: O(n)
Note: The second approach would not work because dict_keys in Python 3 do not support indexing.
Method 3: Accessing key using keys() indexing
Here, we first extracted all the keys and then we implicitly converted them into the Python list to access the element from it.
Python3
test_dict = { "geeks" : 7 , "for" : 1 , "geeks" : 2 }
print ( '2nd key using keys() : ' , list (test_dict.keys())[ 1 ])
|
Output:
2nd key using keys() : for
Method 4: Python Dictionary update() function
To show how to update the dictionary keys using the update() function. Here, when the dictionary is updated, keys are also automatically updated to show the changes.
Python3
Dictionary1 = { 'A' : 'Geeks' , 'B' : 'For' }
print ( "Keys before Dictionary Updation:" )
keys = Dictionary1.keys()
print (keys)
Dictionary1.update({ 'C' : 'Geeks' })
print ( '\nAfter dictionary is updated:' )
print (keys)
|
Output:
Keys before Dictionary Updation:
dict_keys(['B', 'A'])
After dictionary is updated:
dict_keys(['B', 'A', 'C'])