Python – Get first element in List of tuples

In this article. we will discuss how to get the first element in the list of tuples in Python.

Create a list of tuples and display them:

[(1, 'sravan'), (2, 'ojaswi'), (3, 'bobby'), (4, 'rohith'), (5, 'gnanesh')]

Method 1: Using iteration (for loop)

We can iterate through the entire list of tuples and get first by using the index, index-0 will give the first element in each tuple in a list.

Syntax:

for var in list_of_tuple:
print(var[0])

Example: Here we will get the first IE student id from the list of tuples.

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Method 2: Using zip function

Zip is used to combine two or more data/data structures. Here we can use zip() function by using the index as 0 to get the first element.

Syntax: list(zip(*data))[0]

Example: Python code to access first element in List of the tuple.

(1, 2, 3, 4, 5)

Method 3: Using map with itemgetter() method

Here we are using the map function along with itemgetter() method to get the first elements, here also we are using index – 0 to get the first elements. itemgetter() method is available in the operator module, so we need to import operator

Syntax: map(operator.itemgetter(0), data)

Example: Python program to access first elements.

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Method 4: Using map() with lambda expression

Here we are using lambda expression along with map() function, here also we are using index 0 to get the first data.

Syntax: map(lambda x: x[0], data)

Where,

• x is an iterator to get first elements
• data is the list of tuples data

Example: Python code to access first elements.

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Method 5 using list comprehension:

1. It first creates a list of tuples called data.
2. And now use a list comprehension to extract the first element of each tuple.
3. Store it in a new list called result. 
4. Finally, it prints the result list.

[1, 2, 3, 4, 5]

Time complexity: O(n) (where n is the number of tuples in the list)
Auxiliary Space: O(n) (where n is the number of tuples in the list) since we are storing the result in a list.