tinysort 0.1

单词计数示例

目前唯一的mapreduce实现是在内存和串行中，但是 将添加具有并行映射和reduce阶段的实现。

fromcollectionsimportCounterimportjsonimportreimportsysfromtinymr.memoryimportMemMapReduceclassWordCount(MemMapReduce):"""
    The go-to MapReduce example.

    Don't worry, a better example is on its way:
    https://github.com/geowurster/tinymr/issues/11
    """# Counting word occurrence does not benefit from sorting post-map or# post-reduce and our `final_reducer()` doesn't care about key order# so we can disable sorting for a speed boost.sort_map=Falsesort_reduce=Falsesort_final_reduce=Falsedef__init__(self):"""
        Stash a regex to strip off punctuation so we can grab it later.
        """self.pattern=re.compile('[\W_]+')defmapper(self,line):"""
        Take a line of text from the input file and figure out how many
        times each word appears.

        An alternative, simpler implementation would be:

            def mapper(self, item):
                for word in item.split():
                    word = self.pattern.sub('', word)
                    if word:
                        yield word.lower(), 1

        This simpler example is more straightforward, but holds more data
        in-memory.  The implementation below does more work per line but
        potentially has a smaller memory footprint.  Like anything
        MapReduce the implementation benefits greatly from knowing a lot
        about the input data.
        """# Normalize all words to lowercaseline=line.lower().strip()# Strip off punctuationline=[self.pattern.sub('',word)forwordinline]# Filter out empty stringsline=filter(lambdax:x!='',line)# Return an iterable of `(word, count)` pairsreturnCounter(line).items()defreducer(self,key,values):"""
        Just sum the number of times each word appears in the entire
        dataset.

        At this phase `key` is a word and `values` is an iterable producing
        all of the values for that word from the map phase.  Something like:

            key = 'the'
            values = (1, 1, 2, 2, 1)

        The word `the` appeared once on 3 lines and twice on two lines for
        a total of `7` occurrences, so we yield:

            ('the', 7)
        """yieldkey,sum(values)defoutput(self,pairs):"""
        Normally this phase is where the final dataset is written to disk,
        but since we're operating in-memory we just want to re-structure as
        a dictionary.

        `pairs` is an iterator producing `(key, iter(values))` tuples from
        the reduce phase, and since we know that we only produced one key
        from each reduce we want to extract it for easier access later.
        """return{k:tuple(v)[0]fork,vinpairs}wc=WordCount()withopen('LICENSE.txt')asf:out=wc(f)print(json.dumps(out,indent=4,sort_keys=True))

截断输出：

{"a":1,"above":2,"advised":1,"all":1,"and":8,"andor":1}

$ head -10 LICENSE.txt

New BSD License

Copyright (c) 2015, Kevin D. Wurster
All rights reserved.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

* Redistributions of source code must retain the above copyright notice, this
  list of conditions and the following disclaimer.

# Input lineline='Copyright (c) 2015, Kevin D. Wurster'# Sanitized wordswords=['Copyright','c','2015','Kevin','D','Wurster']# Return tuples with word as the first element and count as the secondpairs=[('Copyright',1),('c',1),('2015',1),('Kevin',1),('D',1),('Wurster',1)]

{'2015':[(1,)]'above':[(1,)]'all':[(1,)]'and':[(1,),(1,),(1,)]'are':[(1,),(1,)]'binary':[(1,)]'bsd':[(1,)]'c':[(1,)]'code':[(1,)]}

# The ``reducer()`` receives a key and an iterator of valueskey='the'values=(1,1,1)defreducer(key,values):yieldkey,sum(values)

{'2015':[(1,)]'above':[(1,)]'all':[(1,)]'and':[(3,)]'are':[(2,)]'binary':[(1,)]'bsd':[(1,)]'c':[(1,)]'code':[(1,)]}

values=[('the',(3,)),('in',(1,),]

return{k:tuple(v)[0]fork,vinvalues}

开发

$ git clone https://github.com/geowurster/tinymr.git
$cd tinymr
$ pip install -e .\[dev\]$ py.test tests --cov tinymr --cov-report term-missing

许可证

见LICENSE.txt

变更日志

见CHANGES.md