# How to subtract a list elements using another list in Python

There are two ways you can subtract elements from a list using another list, depending on whether your list has duplicate values or not.

If your list has duplicate values, then you can use a list comprehension with a conditional `if` statement

If your list has no duplicate values, you can transform the lists into sets, subtract the elements, and convert the result into a list.

This tutorial will show you how to use both methods in practice.

## 1. Using a list comprehension and a conditional

To subtract elements from one list using another list, you can use a list comprehension and a conditional `if` statement.

For example, suppose you want to subtract elements from `list_1` using `list_2` as shown below:

``````list_1 = [1, 2, 3, 3, 5, 6, 7, 7, 9]
list_2 = [2, 3, 9]

# subtract elements from list_1 using list_2
result = [x for x in list_1 if x not in list_2]

print(result)
``````

Output:

``````[1, 5, 6, 7, 7]
``````

Here, the elements 2, 3, and 9 are subtracted from `list_1` successfully.

This method is recommended when you have duplicate values in the original list.

## 2. Using set difference

The `set` object in Python is able to subtract elements from a set by only using the minus `-` operator.

If your list has no duplicate values, then you can convert the list to set as follows:

``````list_1 = [1, 2, 3, 3, 5, 6, 7, 7, 9]
list_2 = [2, 3, 9]

# subtract elements as set objects
result = set(list_1) - set(list_2)

# convert result back to list
result = list(result)

print(result)
``````

Output:

``````[1, 5, 6, 7]
``````

Notice that duplicate values are removed when you convert a list to a set.

This is because a set can’t contain duplicate values in Python.

## Conclusion

This tutorial has shown you two easiest ways to subtract a list elements using another list in Python.

Use a list comprehension when you have duplicate values, or use the `set()` function to convert the object and subtract using minus `-` operator.

I hope this tutorial helps. See you in other tutorials!

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