Sometimes, we want to find all occurrences of an element in a list with Python.

In this article, we’ll look at how to find all occurrences of an element in a list with Python.

How to find all occurrences of an element in a list with Python?

To find all occurrences of an element in a list with Python, we can use list comprehension.

For instance, we write:

l = [1, 2, 3, 4, 3, 2, 5, 6, 7]
indexes = [i for i, val in enumerate(l) if val == 3]
print(indexes)

We use enumerate to return an iterator with the tuples for the index and value of each l array entry.

Then we get the i index of each entry if their value is 3 by using the condition val == 3.

And then we assign the array of indexes of the l array where its values is 3 to indexes.

Therefore, indexes is [2, 4].

Conclusion

To find all occurrences of an element in a list with Python, we can use list comprehension.