Python Dictionary keys() method
Last Updated :
16 Jun, 2023
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'])
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