我遇到了哈德普(Hadoop
我现在为reducer类有哪种代码:
public class R_PreprocessAllSMS extends Reducer<Text, Text, Text, Text>{
private final static Text KEY = new Text();
private final static Text VALUE = new Text();
@Override
public void reduce(Text key, Iterable<Text> values, Context context) throws IOException, InterruptedException {
int sum = 0;
for (Text value : values) {
String[] splitString = value.toString().split("t");
sum += Integer.parseInt(splitString[1]);
}
if (sum > 100) {
for (Text value : values) {
String[] splitString = value.toString().split("t");
System.out.println(key.toString() + splitString[0] + " " + splitString[1]);
KEY.set(key);
VALUE.set(splitString[0] + "t" + splitString[1]);
context.write(KEY, VALUE);
}
}
}
}
,但我想第二次搜索给定值并散发我们需要的值。如果不可能,您会建议您建议这样做的建议是什么?谢谢。
而不是循环两次,您可以延迟写入值,直到您知道总和足够高,类似于:
int sum = 0;
List list = new ArrayList<String>();
KEY.set(key);
for (Text value : values) {
String[] splitString = value.toString().split("t");
String line = splitString[0] + "t" + splitString[1];
sum += Integer.parseInt(splitString[1]);
if (sum < 100) {
list.add(line);
} else {
if (!list.isEmpty()) {
for (String val: list) {
VALUE.set(val);
context.write(KEY, VALUE);
}
list.clear();
}
VALUE.set(line);
context.write(KEY, VALUE);
}
}
也许使用两对映射和还原器?您可以一个接一个地称他们为一个。例如,在一个主中创建两个作业。第二获得第一。
JobConf jobConf1 = new JobConf();
JobConf jobConf2 = new JobConf();
Job job1 = new Job(jobConf1);
Job job2 = new Job(jobConf2);
或tou可以看:http://hadoop.apache.org/docs/current/api/org/org/apache/hadoop/mapred/mapred/lib/chainreducer.html