To find the asymmetric difference between two lists in Python:

**Convert**the lists to sets.**Subtract**the sets from one another to find the difference.**Convert**the result back to a list.

Here is an example:

names1 = ["Alice", "Bob", "Charlie", "David"] names2 = ["Bob", "Charlie"] difference = list(set(names1) - set(names2)) print(difference)

Output:

['David', 'Alice']

## Asymmetric Difference between Lists in Python

The asymmetric difference in set theory means given sets A and B, return the elements that are in set A but not in set B. But do not return the elements that are in set B but not in A.

The example you saw above is about the **asymmetric** **difference** between two lists in Python.

For instance:

names1 = ["Alice", "Bob"] names2 = ["Bob", "Charlie"] difference = list(set(names1) - set(names2)) print(difference)

Gives you:

['Alice']

Even though you might expect `["Alice", "Charlie"]`

as neither name occurs in both sets.

But as the asymmetric difference is about finding only the elements that are in set A but not in B, it only returns “Alice”.

To fix this problem, you need to calculate the **symmetric difference** between the two lists.

## Symmetric Difference between Lists in Python

The symmetric difference in set theory means given sets A and B, return the elements that are in set A but not in set B **and** vice versa.

To get the symmetric difference between two lists in Python:

**Convert**the lists to sets.**Use**the built-in`symmetric_difference()`

function of sets to get the symmetric difference.**Convert**the result back to a list.

For example:

names1 = ["Alice", "Bob"] names2 = ["Bob", "Charlie"] difference = list(set(names1).symmetric_difference(set(names2))) print(difference)

Output:

['Charlie', 'Alice']

Now both names that do not occur in both lists are in the result.

## Conclusion

The **Asymmetric difference** between two lists in Python returns the items that list A has but list B does not. This means if list B has an item that is not found in A, it does not count.

To calculate the asymmetric difference in Python lists:

**Convert**the lists to sets.**Compute**the difference by subtracting one set from the other.**Convert**the result to a list.

**Symmetric difference** between two lists in Python returns the items in list A that are not in list B and vice versa. To calculate the symmetric difference in Python lists:

**Convert**the lists to sets.**Compute**the difference with`symmetric_difference()`

method.**Convert**the result to a list.

Thanks for reading. Happy coding!