How to Compute the Difference Between Two Lists in Python?

Subtraction of Lists

The goal is to compute the difference between two lists, x and y, resulting in a new list containing elements from x that are not present in y.

Solution 1: List Comprehension

To preserve the original order from x, use a list comprehension to check which elements are not in y:

<code class="python">[item for item in x if item not in y]</code>

Solution 2: Set Difference

If the order of elements in the resulting list is not important, a set difference can be employed:

<code class="python">list(set(x) - set(y))</code>

Solution 3: Overriding sub

To enable the infix x - y syntax for list subtraction, a custom class can be created that overrides the __sub__ method to implement the desired behavior:

<code class="python">class MyList(list):
    def __sub__(self, other):
        return self.__class__(*[item for item in self if item not in other])</code>

With this class, the subtraction can be performed as follows:

<code class="python">x = MyList(1, 2, 3, 4)
y = MyList(2, 5, 2)
z = x - y   </code>

The above is the detailed content of How to Compute the Difference Between Two Lists in Python?. For more information, please follow other related articles on the PHP Chinese website!