iterate

The iterate reducer will iterate through the values in the list it was given and cycle through those as to "decorate" your data with values from that list.

labeling points

from flume import *

(
    emit(limit=10, start='2015-01-01')
    | put(label=iterate(['a','b','c']))
    | write('stdio')
).execute()

The above would produce the output:

{"time": "2015-01-01T00:00:00.000Z", "label": "a"}
{"time": "2015-01-01T00:00:01.000Z", "label": "b"}
{"time": "2015-01-01T00:00:02.000Z", "label": "c"}
{"time": "2015-01-01T00:00:03.000Z", "label": "a"}
{"time": "2015-01-01T00:00:04.000Z", "label": "b"}
{"time": "2015-01-01T00:00:05.000Z", "label": "c"}
{"time": "2015-01-01T00:00:06.000Z", "label": "a"}
{"time": "2015-01-01T00:00:07.000Z", "label": "b"}
{"time": "2015-01-01T00:00:08.000Z", "label": "c"}
{"time": "2015-01-01T00:00:09.000Z", "label": "a"}