List slicing in Python: How new lists are created and stored in memory

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Yes, when you use slicing on a list in Python, a new list is created containing the elements specified by the slice. This new list occupies a different memory space than the original list.

Explanation of Slicing

Slicing a list in Python creates a new list containing the elements specified by the slice indices. The original list remains unchanged, and the new list is a separate object in memory.

Example and Explanation

list = ['a', 'b', 'c', 'd']
print(list[1:-1]) # Outputs: ['b', 'c']

In this example:
– list[1:-1] creates a new list starting from index 1 up to (but not including) the second-to-last element of the original list.
– The resulting new list is ['b', 'c'].
– This new list is stored in a different memory location from the original list.

Memory and New List Creation

When you perform slicing:
1. A new list object is created.
2. The elements specified by the slice are copied into this new list.
3. The original list remains unchanged.

You can verify that the new list is a different object by comparing their memory addresses using the id() function:

list = ['a', 'b', 'c', 'd']
new_list = list[1:-1]

print(new_list) # Outputs: ['b', 'c']
print(id(list)) # Memory address of the original list
print(id(new_list)) # Memory address of the new list

The id() function will show different addresses for list and new_list, confirming that they are distinct objects in memory.

Summary

• Slicing a list creates a new list with the specified elements.
• The new list occupies a different memory space from the original list.
• The print function will output the contents of the new list when you slice it, not None, because slicing returns a new list object, not None.

Example Code Demonstrating Memory Addresses

list = ['a', 'b', 'c', 'd']
new_list = list[1:-1]

print("Original list:", list)
print("Sliced list:", new_list)

print("Memory address of the original list:", id(list))
print("Memory address of the new sliced list:", id(new_list))

Output:

Original list: ['a', 'b', 'c', 'd']
Sliced list: ['b', 'c']
Memory address of the original list: 140093642714048
Memory address of the new sliced list: 140093642715200

This demonstrates that the original list and the new sliced list are stored at different memory locations, confirming that slicing creates a new list.

 

 

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Source: Google, https://developers.google.com/edu/python/lists#list-methods

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