system-design-primer/solutions/system_design/pastebin/pastebin.py

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2017-03-05 08:05:53 +03:00
# -*- coding: utf-8 -*-
from mrjob.job import MRJob
class HitCounts(MRJob):
def extract_url(self, line):
"""Extract the generated url from the log line."""
pass
def extract_year_month(self, line):
"""Return the year and month portions of the timestamp."""
pass
def mapper(self, _, line):
"""Parse each log line, extract and transform relevant lines.
Emit key value pairs of the form:
(2016-01, url0), 1
(2016-01, url0), 1
(2016-01, url1), 1
"""
url = self.extract_url(line)
period = self.extract_year_month(line)
yield (period, url), 1
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def reducer(self, key, values):
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"""Sum values for each key.
(2016-01, url0), 2
(2016-01, url1), 1
"""
yield key, sum(values)
def steps(self):
"""Run the map and reduce steps."""
return [
self.mr(mapper=self.mapper,
reducer=self.reducer)
]
if __name__ == '__main__':
HitCounts.run()