Dictionary keys as a list in Python

In Python, we will encounter some situations where we need to extract the keys from a dictionary as a list. In this article, we will explore various easy and efficient methods to achieve this.

Using list()

The simplest and most efficient way to convert dictionary keys to lists is by using a built-in list() function.

d = {'a': 1, 'b': 2, 'c': 3}

a = list(d.keys())
print(a)

['a', 'b', 'c']

Explanation:

• a.keys() returns a dict_keys object, which is a view object.
• Wrapping it with list() converts the view into a list.

Using List Comprehension

List Comprehension provide concise and readable way to create a list of keys.

d = {'a': 1, 'b': 2, 'c': 3}

a = [key for key in d]
print(a)

['a', 'b', 'c']

Explanation:

• Iterating directly over the dictionary yields its keys.
• This method avoids calling .keys() explicitly.

Using (* )Unpacking Operator

The unpacking operator (*) can be used to extract keys directly.

d = {'a': 1, 'b': 2, 'c': 3}

a = [*d]
print(a) 

['a', 'b', 'c']

Explanation:

• The unpacking operator expands the dictionary keys into a list.

Using map()

map() function can be used to explicitly iterate over the dictionary.

d = {'a': 1, 'b': 2, 'c': 3}

a = list(map(str,d))
print(a)

['a', 'b', 'c']

Explantion:

• map() applies the identity function (or a custom function) to each key.
• Converting the result to a list yields the desired keys.