Python - Create list of tuples using for loop

In this article, we will discuss how to create a List of Tuples using for loop in Python.

Let's suppose we have a list and we want a create a list of tuples from that list where every element of the tuple will contain the list element and its corresponding index.

Method 1: Using For loop with append() method

Here we will use the for loop along with the append() method. We will iterate through elements of the list and will add a tuple to the resulting list using the append() method.

Example:

L = [5, 4, 2, 5, 6, 1]
res = []

for i in range(len(L)):
    res.append((L[i], i))
    
print("List of Tuples")
print(res)

List of Tuples
[(5, 0), (4, 1), (2, 2), (5, 3), (6, 4), (1, 5)]

Method 2: Using For loop with enumerate() method

Enumerate() method adds a counter to an iterable and returns it in a form of enumerating object. So we can use this function to create the desired list of tuples.

Example:

L = [5, 4, 2, 5, 6, 1]
res = []

for index, element in enumerate(L):
    res.append((element, index))
    
print("List of Tuples")
print(res)

List of Tuples
[(5, 0), (4, 1), (2, 2), (5, 3), (6, 4), (1, 5)]

Method 3: Using zip() function

Using Python's zip() function we can create a list of tuples, for that we will require two lists.

Step-by-step approach:

• Firstly, initialize two variables that will hold some values as a list and the other one will hold the indexes of those values as a list.
• Then use another variable in which we will hold the result of our zip() Operation. Then we need to convert the result of the zip function into a list.
• We will then print the variable.

Below is the implementation of the above approach:

# Defining arr1
arr1 = [5, 4, 2, 5, 6, 1]

# Creating the second array which
# holds the index values of previous array
arr2 = [i for i in range(len(arr1))]

# converting the result into list
res = list(zip(arr1,arr2))

# printing the result
print(res)

[(5, 0), (4, 1), (2, 2), (5, 3), (6, 4), (1, 5)]

Time Complexity - O(min(len(iterable_1), len(iterable_2)))
Auxiliary Space - O(n)