Question

我想获得以字母＆＃34; a-z＆＃34;开头的字数。为此我正在尝试使用此代码，但它只打印以＆＃34; z＆＃34;开头的单词数量。

public void map(LongWritable key, Text value, Context context)

         throws IOException, InterruptedException {

     String line = value.toString();
     StringTokenizer itr = new StringTokenizer(line);

     while( itr.hasMoreTokens()){
         String token= itr.nextToken();

         if(token.startsWith("a-z")){
             word.set("A_Count");
             //word.set("Z_Count");
             context.write(word, ONE);
    }
  }
}

Answer 1

我试过了，它运行正常。

 public class Map extends Mapper<LongWritable, Text, Text, IntWritable> {
            private final IntWritable VALUE = new IntWritable(1);
            private final Text KEY = new Text("COUNT");

            public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
                String line = value.toString();
                StringTokenizer tokenizer = new StringTokenizer(line);
                while (tokenizer.hasMoreTokens()) {
                    String token = tokenizer.nextToken();
                    if(token.startsWith("a-z")){
                    context.write(KEY, VALUE);
                }
            }
         }

我的减速机看起来像

public class Reduce extends Reducer<Text, IntWritable, IntWritable, NullWritable> {
    public void reduce(Text key, Iterable<IntWritable> values, Context context) 
              throws IOException, InterruptedException {
                int sum = 0;
                for (IntWritable val : values) {
                    sum += val.get();
                }
                context.write(new IntWritable(sum),NullWritable.get());
            }
    }

Map reduce - 以字母a-z开头的单词计数

1 个答案: