Python program to Convert a list into a dictionary with index as key

We are given a list and our task is to convert it into a dictionary where each element’s index in the list becomes the key and the element itself becomes the corresponding value. For example, if we have a list like: ['apple', 'banana', 'cherry'] then the output will be {0: 'apple', 1: 'banana', 2: 'cherry'}.

Using enumerate()

enumerate() function allows us to get both the index and value from the list simultaneously and makes this a simple and efficient way to create a dictionary where the index is the key.

li = ['aryan', 'harsh', 'kunal']

res = dict(enumerate(li))

print(res)

{0: 'apple', 1: 'banana', 2: 'cherry'}

Explanation: enumerate(li) generates pairs like (0, 'apple'), (1, 'banana'), (2, 'cherry') abnd dict() converts these pairs into a dictionary

Using a Dictionary Comprehension

This method uses dictionary comprehension to iterate over the list and create key-value pairs where the index becomes the key and the element is the value.

li = ['aryan', 'harsh', 'kunal']

res = {i: li[i] for i in range(len(li))}

print(res)

{0: 'aryan', 1: 'harsh', 2: 'kunal'}

Explanation: {i: li[i] for i in range(len(li))} creates key-value pairs where the key is the index i and the value is the corresponding element li[i].

Using zip() with range()

zip() function can be used to combine two iterables: one for the indices (range(len(li))) and the other for the list values (li). This creates pairs of indices and elements which can then be converted into a dictionary.

li = ['aryan', 'harsh', 'kunal']

res = dict(zip(range(len(li)), li))

print(res)

{0: 'aryan', 1: 'harsh', 2: 'kunal'}

Explanation of Code:

• zip(range(len(li)), li) pairs each index in range(len(li)) with the corresponding element in li.
• dict() converts these pairs into a dictionary.

Using a for Loop

We can also use a simple for loop to iterate through the list and add key-value pairs to an empty dictionary.

li = ['aryan', 'harsh', 'kunal']
res = {}

for i in range(len(li)):
    res[i] = li[i]
    
print(res)

{0: 'aryan', 1: 'harsh', 2: 'kunal'}

Explanation: for loop iterates over the indices of the list and each index is used as a key in the dictionary with the corresponding list element as the value.