datafu.pig.stats
Class WilsonBinConf

java.lang.Object
  org.apache.pig.EvalFunc<T>
      datafu.pig.util.SimpleEvalFunc<org.apache.pig.data.Tuple>
          datafu.pig.stats.WilsonBinConf

public class WilsonBinConf
extends SimpleEvalFunc<org.apache.pig.data.Tuple>

Computes the Wilsonian binomial proportion confidence interval

Constructor requires the confidence interval (alpha) parameter, and the parameters are the number of positive (success) outcomes and the total number of observations. The UDF returns the (lower,upper) confidence interval.

Example:

 -- the Wilsonian binomial proportion confidence interval for scoring
 %declare WILSON_ALPHA 0.10

 define WilsonBinConf      datafu.pig.stats.WilsonBinConf('$WILSON_ALPHA'); 

 bar = FOREACH foo GENERATE WilsonBinConf(successes, totals).lower as score;
 quux = ORDER bar BY score DESC;
 top = LIMIT quux 10;
 
 

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

WilsonBinConf(double alpha)

WilsonBinConf(java.lang.String alpha)

Method Summary

org.apache.pig.data.Tuple	binconf(java.lang.Long x, java.lang.Long n)
org.apache.pig.data.Tuple	call(java.lang.Number x, java.lang.Number n)
org.apache.pig.impl.logicalLayer.schema.Schema	outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input) Override outputSchema so we can verify the input schema at pig compile time, instead of runtime

Methods inherited from class datafu.pig.util.SimpleEvalFunc

exec, getReturnType

Methods inherited from class org.apache.pig.EvalFunc

finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLogger, getPigLogger, getReporter, 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

WilsonBinConf

public WilsonBinConf(double alpha)

WilsonBinConf

public WilsonBinConf(java.lang.String alpha)

Method Detail

call

public org.apache.pig.data.Tuple call(java.lang.Number x,
                                      java.lang.Number n)
                               throws java.io.IOException

Throws:

java.io.IOException

binconf

public org.apache.pig.data.Tuple binconf(java.lang.Long x,
                                         java.lang.Long n)
                                  throws java.io.IOException

Parameters:

x - The number of positive (success) outcomes

n - The number of observations

Returns:

The (lower,upper) confidence interval

Throws:

java.io.IOException

outputSchema

public org.apache.pig.impl.logicalLayer.schema.Schema outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input)

Description copied from class: SimpleEvalFunc

Override outputSchema so we can verify the input schema at pig compile time, instead of runtime

Overrides:

outputSchema in class SimpleEvalFunc<org.apache.pig.data.Tuple>

Parameters:

input - input schema

Returns:

call to super.outputSchema in case schema was defined elsewhere