How slicing in Python works

In Python, slicing is a technique used to extract a portion (or a subset) of elements from a sequence such as a string, list, or tuple. Slicing allows you to specify the start and end indices to define the range of elements you want to extract. The syntax for slicing is as follows:

sequence[start:end:step]

Here’s a breakdown of each component:

• sequence: Refers to the sequence (e.g., string, list, or tuple) from which you want to extract elements.
• start: Specifies the index at which the slice begins (inclusive). If omitted, the slice starts from the beginning of the sequence.
• end: Specifies the index at which the slice ends (exclusive). If omitted, the slice continues until the end of the sequence.
• step: Specifies the step size or the increment between the indices. If omitted, the default step is 1.

Some examples will illustrate the usage of slicing:

my_list = [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

# Extract a portion of the list
subset = my_list[2:6]  # [2, 3, 4, 5]

# Extract elements with a step size
step_subset = my_list[1:9:2]  # [1, 3, 5, 7]

# Extract elements from a specific index until the end
end_subset = my_list[5:]  # [5, 6, 7, 8, 9]

# Extract elements from the beginning until a specific index
start_subset = my_list[:4]  # [0, 1, 2, 3]

# Reverse the list
reversed_list = my_list[::-1]  # [9, 8, 7, 6, 5, 4, 3, 2, 1, 0]

In these examples, my_list is a list containing elements from 0 to 9. Various slicing techniques are used to extract subsets or modify the order of the elements. Slicing can also be applied to strings and tuples using the same syntax.

It’s important to note that when slicing, the original sequence remains unchanged, and a new sequence containing the sliced elements is returned.