def slice(source: Observable[_T]) -> Observable[_T]:
"""The partially applied slice operator.
Slices the given observable. It is basically a wrapper around the operators
:func:`skip <reactivex.operators.skip>`,
:func:`skip_last <reactivex.operators.skip_last>`,
:func:`take <reactivex.operators.take>`,
:func:`take_last <reactivex.operators.take_last>` and
:func:`filter <reactivex.operators.filter>`.
The following diagram helps you remember how slices works with streams.
Positive numbers are relative to the start of the events, while negative
numbers are relative to the end (close) of the stream.
.. code::
r---e---a---c---t---i---v---e---!
0 1 2 3 4 5 6 7 8
-8 -7 -6 -5 -4 -3 -2 -1 0
Examples:
>>> result = source.slice(1, 10)
>>> result = source.slice(1, -2)
>>> result = source.slice(1, -1, 2)
Args:
source: Observable to slice
Returns:
A sliced observable sequence.
"""
if _stop >= 0:
pipeline.append(ops.take(_stop))
if _start > 0:
pipeline.append(ops.skip(_start))
elif _start < 0:
pipeline.append(ops.take_last(-_start))
if _stop < 0:
pipeline.append(ops.skip_last(-_stop))
if _step > 1:
pipeline.append(ops.filter_indexed(lambda x, i: i % _step == 0))
elif _step < 0:
# Reversing events is not supported
raise TypeError("Negative step not supported.")
return source.pipe(*pipeline)
def create():
return xs.pipe(ops.take_last(1))
