Edit : instead of buffering in Hash and then emitting at cleanup you can
use a combiner. Likely slower but easier to code if speed is not your
main concern
Le 01/03/2015 13:41, Ulul a écrit :
Hi
I probably misunderstood your question because my impression is that
it's typically a job for a reducer. Emit "local" min and max with two
keys from each mapper and you will easily get gobal min and max in reducer
Ulul
Le 28/02/2015 14:10, Shahab Yunus a écrit :
As far as I understand cleanup is called per task. In your case I.e.
per map task. To get an overall count or measure, you need to
aggregate it yourself after the job is done.
One way to do that is to use counters and then merge them
programmatically at the end of the job.
Regards,
Shahab
On Saturday, February 28, 2015, unmesha sreeveni
<unmeshab...@gmail.com <mailto:unmeshab...@gmail.com>> wrote:
I am having an input file, which contains last column as class label
7.4 0.29 0.5 1.8 0.042 35 127 0.9937 3.45 0.5 10.2 7 1
10 0.41 0.45 6.2 0.071 6 14 0.99702 3.21 0.49 11.8 7 -1
7.8 0.26 0.27 1.9 0.051 52 195 0.9928 3.23 0.5 10.9 6 1
6.9 0.32 0.3 1.8 0.036 28 117 0.99269 3.24 0.48 11 6 1
...................
I am trying to get the unique class label of the whole file.
Inorder to get the same I am doing the below code.
/public class MyMapper extends Mapper<LongWritable, Text,
IntWritable, FourvalueWritable>{/
/ Set<String> uniqueLabel = new HashSet();/
/
/
/ public void map(LongWritable key,Text value,Context context){/
/ //Last column of input is classlabel./
/ Vector<String> cls = CustomParam.customLabel(line,
delimiter, classindex); // /
/ uniqueLabel.add(cls.get(0));/
/ }/
/ public void cleanup(Context context) throws IOException{/
/ //find min and max label/
/ context.getCounter(UpdateCost.MINLABEL).setValue(Long.valueOf(minLabel));/
/ context.getCounter(UpdateCost.MAXLABEL).setValue(Long.valueOf(maxLabel));/
/}/
Cleanup is only executed for once.
And after each map whether "Set uniqueLabel = new HashSet();" the
set get updated,Hope that set get updated for each map?
Hope I am able to get the uniqueLabel of the whole file in cleanup
Please suggest if I am wrong.
Thanks in advance.
