108 lines
2.5 KiB
Python
108 lines
2.5 KiB
Python
"""
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A coroutine to compute a running average.
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Testing ``averager`` by itself::
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>>> coro_avg = averager()
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>>> next(coro_avg)
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>>> coro_avg.send(10)
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>>> coro_avg.send(30)
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>>> coro_avg.send(6.5)
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>>> coro_avg.send(None)
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Traceback (most recent call last):
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...
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StopIteration: Result(count=3, average=15.5)
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Driving it with ``yield from``::
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>>> def summarize(results):
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... while True:
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... result = yield from averager()
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... results.append(result)
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...
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>>> results = []
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>>> summary = summarize(results)
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>>> next(summary)
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>>> for height in data['girls;m']:
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... summary.send(height)
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...
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>>> summary.send(None)
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>>> for height in data['boys;m']:
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... summary.send(height)
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...
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>>> summary.send(None)
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>>> results == [
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... Result(count=10, average=1.4279999999999997),
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... Result(count=9, average=1.3888888888888888)
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... ]
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True
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"""
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# tag::YIELD_FROM_AVERAGER[]
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from collections import namedtuple
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Result = namedtuple('Result', 'count average')
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# the subgenerator
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def averager(): # <1>
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total = 0.0
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count = 0
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average = None
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while True:
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term = yield # <2>
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if term is None: # <3>
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break
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total += term
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count += 1
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average = total/count
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return Result(count, average) # <4>
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# the delegating generator
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def grouper(results, key): # <5>
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while True: # <6>
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results[key] = yield from averager() # <7>
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# the client code, a.k.a. the caller
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def main(data): # <8>
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results = {}
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for key, values in data.items():
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group = grouper(results, key) # <9>
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next(group) # <10>
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for value in values:
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group.send(value) # <11>
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group.send(None) # important! <12>
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# print(results) # uncomment to debug
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report(results)
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# output report
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def report(results):
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for key, result in sorted(results.items()):
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group, unit = key.split(';')
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print(f'{result.count:2} {group:5}',
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f'averaging {result.average:.2f}{unit}')
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data = {
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'girls;kg':
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[40.9, 38.5, 44.3, 42.2, 45.2, 41.7, 44.5, 38.0, 40.6, 44.5],
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'girls;m':
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[1.6, 1.51, 1.4, 1.3, 1.41, 1.39, 1.33, 1.46, 1.45, 1.43],
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'boys;kg':
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[39.0, 40.8, 43.2, 40.8, 43.1, 38.6, 41.4, 40.6, 36.3],
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'boys;m':
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[1.38, 1.5, 1.32, 1.25, 1.37, 1.48, 1.25, 1.49, 1.46],
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}
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if __name__ == '__main__':
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main(data)
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# end::YIELD_FROM_AVERAGER[]
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