Question

我正在尝试运行mapreduce作业，该作业在我的机器上运行完美，但不会在另一台机器上运行。我的映射器在生产机器上输出错误。

实际输出应该类似于

1,1   M,1,1
1,1   M,2,3
1,2   M,1,1

等等

mapper输出有一些额外的值，就像这样

0   1,1   M,1,1
0   1,1   M,2,3
0   1,2   M,1,1

除了实际值（即正确的outpt，加上一些额外的错误值）映射器代码是

  public static class Map extends Mapper<LongWritable, Text, Text, Text> {

//output keys and values
 private Text key_ikM = new Text();
 private Text key_ikMt = new Text();
 private Text outp = new Text();
 private Text outpt = new Text();

    public void map(LongWritable key, Text value, Context context) throws IOException, InterruptedException {
/*the input is row no, column number, value*/
String[] line = value.toString().split(",", 3);

String row_i = line[0];
String col_j = line[1];
String val_ij = line[2];

/*code to calculate max value of row_id in the dataset*/

int max_row=3;
//int max_col=5;

for(int k=1; k<=max_row; k++){
    String keyM = row_i + "," + Integer.toString(k);

    String value_ij = "M" + "," + col_j + "," + val_ij;

key_ikM.set(keyM);  
    outp.set(value_ij);

context.write(key_ikM, outp);
}

for(int i=1; i<=max_row; i++){
    String keyMt = Integer.toString(i) + "," + row_i;

    String value_ik = "Mt" + "," + col_j + "," + val_ij;

key_ikMt.set(keyMt);  
    outpt.set(value_ik);      
context.write(key_ikMt, outpt);    // transpose of M
   }
  }
 }

其中row_i，col_j和val_ij取自输入。

为什么要生成这些额外的0？它是由Integer.toString（）创建的吗？我应该用别的吗？请帮忙。谢谢。

Mapper输出在一台机器中有额外的0值;在其他中给出正确的输出

0 个答案: