How Can I Remove All Instances of a Value from a Python List?

Removing All Occurrences of a Value from a List

While Python's remove() method allows for the removal of a single occurrence of a value from a list, it may sometimes be necessary to remove all occurrences of that value. Here's a guide to achieving this:

Functional Approach:

In Python, the built-in filter() function provides a straightforward way to remove specific elements from a list based on a given condition. By using lambda expressions or manual comparisons, we can filter out all occurrences of the target value:

# Python 3.x
>>> x = [1, 2, 3, 2, 2, 2, 3, 4]
>>> list(filter((2).__ne__, x))
[1, 3, 3, 4]

This filters and returns a new list containing elements that are not equal to the removal target (2), effectively removing all occurrences of 2.

Alternatively:

>>> list(filter(lambda a: a != 2, x))
[1, 3, 3, 4]

Here, the lambda expression directly compares each element to 2 and returns True if it's not equal, filtering out the target values.

For Python 2.x, the filter function returns an iterator:

# Python 2.x
>>> filter(lambda a: a != 2, x)
[1, 3, 3, 4]

In either Python version, the result is a list or iterator containing the elements that satisfy the filter conditions, effectively excluding the target value from the original list.

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