Slicing

Slicing is Subscript Notation to get a subrange from a sequence.

For any array, you can slice its contents.

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

You use the start:stop:step format.

sliced = arr[2:5:1]
> [3,4,5]

The start:stop:step format:

You can skip values.

If you skip the start, it starts at index 0.

sliced = arr[:5:1]
> [1,2,3,4,5]

If you skip the end, it goes until the end of the list.

sliced = arr[2::1]
> [3,4,5,6,7,8,9]

If you skip the step, it defaults to 1.

sliced = arr[2:5:]
> [3,4,5]

You can even skip the : entirely.

sliced = arr[2:5]
> [3,4,5]

You can set negative values for all variables.

Start and end with negative values just use the index starting from the end of the array.

Step with negative values traverses the array backwards.

sliced = arr[4:1:-1]
> [5,4,3]

Important: If you use a negative step, start must be bigger than stop.

When both start and stop are omitted but step is negative, the array gets reversed.

sliced = arr[::-1]
> [9,8,7,6,5,4,3,2,1]

You can also skip indexes with step =/= |1|

sliced = arr[::2]
sliced_reversed = arr[::-2]
> [1,3,5,7,9] # Skipping one
> [9,7,5,3,1] # Skipping one from the back

Equinox