def _reduce(accumulator: Accumulator,
seed: Any = NotSet) -> Callable[[Observable], Observable]:
"""Applies an accumulator function over an observable sequence,
returning the result of the aggregation as a single element in the
result sequence. The specified seed value is used as the initial
accumulator value.
For aggregation behavior with incremental intermediate results, see
`scan()`.
Examples:
>>> res = reduce(lambda acc, x: acc + x)
>>> res = reduce(lambda acc, x: acc + x, 0)
Args:
accumulator: An accumulator function to be
invoked on each element.
seed: Optional initial accumulator value.
Returns:
An operator function that takes an observable source and returns
an observable sequence containing a single element with the
final accumulator value.
"""
if seed is not NotSet:
scanner = ops.scan(accumulator, seed=seed)
return pipe(scanner, ops.last_or_default(default_value=seed))
return pipe(ops.scan(accumulator), ops.last())
def create():
def predicate(x):
if x < 4:
return x % 2 == 1
else:
raise Exception(ex)
return xs.pipe(_.last_or_default(predicate, 0))
def create():
def predicate(x):
if x < 4:
return x % 2 == 1
else:
raise Exception(ex)
return xs.pipe(_.last_or_default(predicate, 0))
def _scan(source):
if isinstance(source, rs.MuxObservable):
return scan_mux(accumulator, seed, reduce)(source)
else:
_seed = seed() if callable(seed) else seed
if reduce is False:
return rx.pipe(
ops.scan(accumulator, _seed),
ops.default_if_empty(default_value=_seed),
)(source)
else:
return rx.pipe(
ops.scan(accumulator, _seed),
ops.last_or_default(default_value=_seed),
)(source)
def last_or_default(source: Observable) -> Observable:
"""Return last or default element.
Examples:
>>> res = _last_or_default(source)
Args:
source: Observable sequence to get the last item from.
Returns:
Observable sequence containing the last element in the
observable sequence.
"""
if predicate:
return source.pipe(
ops.filter(predicate),
ops.last_or_default(None, default_value),
)
return last_or_default_async(source, True, default_value)
def last_or_default(source: Observable) -> Observable:
"""Return last or default element.
Examples:
>>> res = _last_or_default(source)
Args:
source: Observable sequence to get the last item from.
Returns:
Observable sequence containing the last element in the
observable sequence.
"""
if predicate:
return source.pipe(
ops.filter(predicate),
ops.last_or_default(None, default_value),
)
return last_or_default_async(source, True, default_value)
def create():
def predicate(x):
return x % 2 == 1
return xs.pipe(_.last_or_default(predicate, 0))
def create():
return xs.pipe(_.last_or_default(None, 0))
def create():
def predicate(x):
return x % 2 == 1
return xs.pipe(_.last_or_default(predicate, 0))
def create():
return xs.pipe(_.last_or_default(None, 0))