How to find the index of an item in a list in Python?

To perform certain index-based operations while programming we need to access the index of an element in the list. In this Python example we will discuss some o the ways to find the index of an item in a list in Python.

Some of the topics which will be helpful for understanding the program implementation better are:

• List in Python
• Function in Python
• Dictionary in Python
• For loop in Python

1. Using the index() method

The index() method returns the index of the first occurrence of an item in a list and a ValueError is raised if the element is not found.

Now let’s implement a program to find the index of an item in a list in Python.

my_list = [1, 2, 3, 4, 5]
item = 3
index = my_list.index(item)
print(index)

Output
2

2. Using enumerate() function

The enumerate() function in Python takes an iterable as an argument and returns a tuple containing the index and the item at that index.

Here is an example.

my_list = [1, 2, 3, 4, 5]
item = 3
for i, val in enumerate(my_list):
  if val == item:
    index = i
    break
print(index)

Output
2

3. Using the bisect module

The bisect module in Python has bisect_left() function that can be used to find the index of an item in a sorted list.

Here is an example.

import bisect

my_list = [1, 2, 3, 4, 5]
item = 3
index = bisect.bisect_left(my_list, item)
print(index)

Output
2

4. Using for loop and range() function

You can create a range of indices that matches the length of the list and iterate over them. Then, you can use the current index to access the corresponding item in the list.

Here is an example.

countries = ['USA', 'Canada', 'UK', 'Germany', 'Japan']

for i in range(len(countries)):
  print(i, countries[i])

Output
0 USA
1 Canada
2 UK
3 Germany
4 Japan

4. Conclusion

In this Python example, we discussed the index() method, for loop, the enumerate() function, or the bisect module. to find the index of an item in a list in Python.

Helpful Links

Please follow the Python tutorial series or the menu in the sidebar for the complete tutorial series.

Also for examples in Python and practice please refer to Python Examples.

Complete code samples are present on Github project.

Recommended Books

An investment in knowledge always pays the best interest. I hope you like the tutorial. Do come back for more because learning paves way for a better understanding

Do not forget to share and Subscribe.

Happy coding!! ?

Recommended -