datafu.pig.stats
Class StreamingMedian

java.lang.Object
  org.apache.pig.EvalFunc<T>
      org.apache.pig.AccumulatorEvalFunc<org.apache.pig.data.Tuple>
          datafu.pig.stats.StreamingQuantile
              datafu.pig.stats.StreamingMedian

All Implemented Interfaces:

org.apache.pig.Accumulator<org.apache.pig.data.Tuple>

public class StreamingMedian
extends StreamingQuantile

Computes the approximate median for a (not necessarily sorted) input bag, using the Munro-Paterson algorithm. This is a convenience wrapper around StreamingQuantile.

N.B., all the data is pushed to a single reducer per key, so make sure some partitioning is done (e.g., group by 'day') if the data is too large. That is, this isn't distributed median.

See Also:

StreamingQuantile

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

StreamingMedian()

Method Summary

Methods inherited from class datafu.pig.stats.StreamingQuantile

accumulate, cleanup, getValue, outputSchema

Methods inherited from class org.apache.pig.AccumulatorEvalFunc

exec

Methods inherited from class org.apache.pig.EvalFunc

finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, isAsynchronous, progress, setInputSchema, setPigLogger, setReporter, setUDFContextSignature, warn

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

StreamingMedian

public StreamingMedian()