Clear a List in Python

In Python, clearing a list means removing all elements from it while keeping the list itself intact. Python provides several ways to achieve this, such as using the clear() method, reassigning an empty list, slicing, and using del. In this tutorial, we will explore different methods with examples.

Examples

1. Clear a List Using the clear() Method

The clear() method removes all elements from the list, leaving it empty.

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# Creating a list with elements
numbers = [1, 2, 3, 4, 5]

# Clearing the list using clear()
numbers.clear()

# Printing the updated list
print("Updated List:", numbers)

Here, we first define a list numbers containing five integers. The clear() method is then called on the list, which removes all elements from numbers but keeps the list itself intact.

Output:

Updated List: []

2. Reassigning an Empty List

Reassigning a list variable to an empty list effectively removes all elements.

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# Creating a list with elements
fruits = ["apple", "banana", "cherry"]

# Reassigning an empty list
fruits = []

# Printing the updated list
print("Updated List:", fruits)

Here, we initialize a list fruits with three elements. Instead of modifying the existing list, we reassign the variable fruits to an empty list [], which clears all elements by creating a new empty list.

Output:

Updated List: []

3. Clear a List Using Slicing ([:])

Assigning an empty slice to a list removes all elements without changing its reference.

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# Creating a list with elements
colors = ["red", "blue", "green"]

# Clearing the list using slicing
colors[:] = []

# Printing the updated list
print("Updated List:", colors)

In this example, the list colors is cleared using slicing colors[:]. This operation removes all elements while maintaining the original reference to the list, unlike reassignment.

Output:

Updated List: []

4. Clear a List Using the del Statement

The del statement can be used to delete all elements in a list while keeping the list itself.

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# Creating a list with elements
animals = ["dog", "cat", "rabbit"]

# Clearing the list using del
del animals[:]

# Printing the updated list
print("Updated List:", animals)

Here, the del statement with slicing del animals[:] removes all elements from the list while keeping the reference unchanged.

Output:

Updated List: []

Conclusion

  1. clear(): Removes all elements while keeping the original list.
  2. Reassigning an Empty List: Creates a new empty list and assigns it to the variable.
  3. Slicing ([:]): Removes all elements without changing the reference.
  4. del Statement: Deletes all elements while keeping the list.

For most cases, using clear() is the recommended approach as it is more readable and explicit.