Thanks! That got me going, and the program works now :)
On Tue, Sep 7, 2010 at 10:50 PM, Harsh J <qwertyman...@gmail.com> wrote:
> There's jc.setMapOutput{Key, Value} methods you can use for this.
>
> Harsh J
> http://harshj.com
>
> On 8 Sep 2010 10:21, "Clarence Gardner" <clarence1...@gmail.com> wrote:
>
> I'm writing my first m/r program, and seem to be having problems describing
> the types of my key-value pairs.
>
> I have this mapper
> public static class Map
> extends Mapper<LongWritable, Text, Text, CensusData>
> and this reducer
> public static class Reduce
> extends Reducer<Text, CensusData, Text, IntWritable>
>
> and this in my run() method
> job.setMapperClass(Map.class);
> job.setReducerClass(Reduce.class);
>
> job.setOutputKeyClass(Text.class);
> job.setOutputValueClass(IntWritable.class);
>
> I'm assuming that the types given to setOutput...Class should be the types
> output by the reducer. There doesn't seem to be a way to tell the Context
> object what the types are. Unfortunately, all the examples I see on the web
> output the same types from both the mapper and reducer.
>
> I'm getting this error from my "context.write(county, cd)" statement in my
> mapper:
> java.io.IOException: Type mismatch in value from map: expected
> org.apache.hadoop.io.IntWritable, recieved CensusData
> at
> org.apache.hadoop.mapred.MapTask$MapOutputBuffer.collect(MapTask.java:850)
> at
> org.apache.hadoop.mapred.MapTask$NewOutputCollector.write(MapTask.java:541)
> at
> org.apache.hadoop.mapreduce.TaskInputOutputContext.write(TaskInputOutputContext.java:80)
> at CountyAgi$Map.map(CountyAgi.java:31)
>
> I tried changing setOutputKeyClass to expect LongWritable instead of
> IntWriteable, and the error changed correspondingly. So, how would I say
> that the mapper outputs (Text, CensusData) and the reducer outputs (Text,
> IntWritable)?
>
>
