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  • 理解MapReduce

    1.用Python编写WordCount程序并提交任务

    程序

    WordCount

    输入

    一个包含大量单词的文本文件

    输出

    文件中每个单词及其出现次数(频数),并按照单词字母顺序排序,每个单词和其频数占一行,单词和频数之间有间隔

    import sys
    for i in stdin:
         i = i.strip()
         words = i.split()
         for word in words:
             print '%s	%s' % (word,1)
    from operator import itemgetter
    import sys
      
    current_word = None
    current_count = 0
    word = None
      
    for line in sys.stdin:
        line = line.strip()
        word, count = line.split('	', 1)
        try:
            count = int(count)
        except ValueError:
            continue
        if current_word == word:
            current_count += count
        else:
            if current_word:
                print "%s	%s" % (current_word, current_count)
            current_count = count
            current_word = word
      
    if word == current_word:
        print "%s	%s" % (current_word, current_count)
    chmod a+x /home/hadoop/wc/mapper.py
    chmod a+x /home/hadoop/wc/reducer.py
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  • 原文地址:https://www.cnblogs.com/0056a/p/9021969.html
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