slice

Properties

>>> dir(slice)
['__class__', '__delattr__', '__dir__', '__doc__', '__eq__', '__format__', '__ge__', '__getattribute__', '__gt__', '__hash__', '__init__', '__init_subclass__', '__le__', '__lt__', '__ne__', '__new__', '__reduce__', '__reduce_ex__', '__repr__', '__setattr__', '__sizeof__', '__str__', '__subclasshook__', 'indices', 'start', 'step', 'stop']

Definition

A slice object stores the start, stop, and step parameters for slicing sequences. Slice objects are created implicitly with seq[start:stop:step] or explicitly with slice(start, stop, step).

>>> s = slice(1, 5, 2)
>>> s.start, s.stop, s.step
(1, 5, 2)
>>> [0,1,2,3,4,5][s]
[1, 3]

Creating slices

slice(stop)            # start=None, step=None
slice(start, stop)     # step=None
slice(start, stop, step)

Using indices()

indices(length) normalizes the slice for a sequence of given length, returning (start, stop, step) with bounds applied—useful when implementing __getitem__.

>>> s = slice(-3, None, 2)
>>> s.indices(6)
(3, 6, 2)

Dunder methods

Dunder Method	Operation	Example (normal syntax)	Example (dunder call)
__reduce__	Pickle support	import pickle; pickle.dumps(slice(1,5))	slice(1,5).__reduce__()
__repr__	Representation	repr(slice(1,5,2)) → 'slice(1, 5, 2)'	slice(1,5,2).__repr__()
__eq__	Equality	slice(1,5)==slice(1,5) → True	slice(1,5).__eq__(slice(1,5))
(attributes)	Access start/stop/step	s.start, s.stop, s.step	—