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import contextlib
import itertools
from collections import deque
from collections.abc import Generator, Iterable
from typing import Any
class DumpData(Exception):
"""Exception used to indicate the window's contents should be dumped."""
class ClearWindow(Exception):
"""Exception used to indicate the window should be cleared."""
def moving_window_average_gen(
data: Iterable[float] = (),
window_size: int = 3,
) -> Generator[float | int | None, float, None]:
"""Run a nanoservice for a simple moving window average.
Starter: https://docs.python.org/3/library/collections.html#deque-recipes
Args:
data: Data to pre-fill into the deque, to avoid bias from little data.
window_size: Window size for the moving window average.
Returns:
Generator that intakes a new value and returns an average.
"""
window = deque(data, maxlen=window_size)
current_sum = sum(window)
def on_new_value(value: Any) -> float:
if not isinstance(value, int | float):
raise TypeError(f"Please send in numbers, not {type(value)}.")
nonlocal current_sum
current_sum += value if len(window) < window_size else value - window.popleft()
window.append(value)
return current_sum / len(window)
out_value: float | None = None
while True:
try:
print("MWA nanoservice: waiting after yield.")
in_value = yield out_value
except DumpData:
print("MWA nanoservice: providing length.")
yield len(window)
print("MWA nanoservice: dumping data.")
# NOTE: use islice since deque doesn't support slicing
yield from itertools.islice(window, len(window) - 1)
out_value = window[-1] # Trick to avoid extra next call
continue
except ClearWindow:
print("MWA nanoservice: clearing window.")
window.clear()
current_sum = 0
out_value = None
continue
except GeneratorExit:
print("MWA nanoservice: exiting.")
raise
try:
out_value = on_new_value(in_value)
except TypeError:
print(f"MWA nanoservice: rejected input {in_value!r}.")
out_value = None
def demo() -> None:
mwa_nanoservice = moving_window_average_gen()
next(mwa_nanoservice) # Initialize to first yield
# 1. General usage
assert mwa_nanoservice.send(5) == 5
assert mwa_nanoservice.send(7) == 6
# Check we handle someone forgetting a value or sending wrong type
assert next(mwa_nanoservice) is None
assert mwa_nanoservice.send("unexpected") is None # type: ignore[arg-type]
assert mwa_nanoservice.send(9) == 7
assert mwa_nanoservice.send(11) == 9
# 2. Dumping all data from moving window
num_datapoints = mwa_nanoservice.throw(DumpData)
assert tuple(
next(mwa_nanoservice) for _ in range(num_datapoints) # type: ignore[arg-type]
) == (7, 9, 11)
assert mwa_nanoservice.send(13) == 11
# 3. Clearing the window's contents
assert mwa_nanoservice.throw(ClearWindow) is None
assert mwa_nanoservice.send(15) == 15
# 4. Shut down the nanoservice
mwa_nanoservice.close()
with contextlib.suppress(StopIteration):
assert mwa_nanoservice.send(17) is None
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