MRJob - Python - How to return null when division is 0/value

Question

How can I modify this code so when senti_avg is not divisible (0/value), reducer() outputs NULL or NONE instead of crashing?

def reducer(self, bs_id, value):
    avg_data = list(value)
    senti_sum = sum([a[0] for a in avg_data])
    word_sum = sum([a[1] for a in avg_data])
    senti_avg = senti_sum/float(word_sum)

    yield (bs_id, senti_avg)

value/0 makes sense, but my word_count is always > 0, maybe there is an error with my code. Don't know why it is returning error for 0/value... — Nicolas Hung, Apr 09 '13 at 14:19
Perhaps; if `avg_data` is empty, both `senti_sum` and `word_sum` would be 0, leading to `0/0` and a `ZeroDivisionError`. — Martijn Pieters, Apr 09 '13 at 14:20

score 4 · Answer 1 · answered Apr 09 '13 at 14:08

4

You use python exception handling:

try:
    senti_avg = senti_sum/float(word_sum)
except ZeroDivisionError:
    senti_avg = None

answered Apr 09 '13 at 14:08

Martijn Pieters

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MRJob - Python - How to return null when division is 0/value

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