count

The count reducer simply counts the number of points that have passed through this point in the pipeline.

counting points

from flume import *

(
    emit(limit=10, start='2015-01-01')
    | reduce(count=count())
    | write('stdio')
).execute()

The above would produce the output:

{"count": 10, "time": "2015-01-01T00:00:00.000Z"}