MapReduce: ValueError: too many values to unpack (expected 2)

Question

我是运行 MapReduce 中的以下 Python 代码：

from mrjob.job import MRJob
import collections

bigram = collections.defaultdict(float)
unigram = collections.defaultdict(float)


class MRWordFreqCount(MRJob):

    def mapper(self, _, line):
        # Now we loop over lines in the system input
        line = line.strip().split()
        # go through each word in sentence
        i = 0
        for word in line:
            if i > 0:
                hist = word
            else:
                hist = ''

            word = CleanWord(word)  # Get the new word

            # If CleanWord didn't return a string, move on
            if word == None: continue

            i += 1
            yield word.lower(), hist.lower(), 1.0

if __name__ == '__main__':
    MRWordFreqCount.run()

我收到错误：ValueError：要解压的值太多（预期为 2），但我不明白为什么。有什么建议么？我运行的 cmd 行代码是： python myjob.py Test.txt --mapper

Answer 1

在 MapReduce 作业中，您只发出键值对。为此，您可以应用以下类型的策略：

yield (word.lower(), hist.lower()), 1.0

MapReduce: ValueError: too many values to unpack (expected 2)

MapReduce: ValueError: too many values to unpack (expected 2)

python

hadoop

mapreduce

mrjob