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https://issues.apache.org/jira/browse/PIG-1678?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel
]
David Ciemiewicz updated PIG-1678:
----------------------------------
Description:
I would like to have a trivial way to bind and invoke Java library functions
from within Pig without creating wrapper functions in Java.
For instance, I need functions out of the Apache Commons Math library
(http://commons.apache.org/math/) such as
BetaDistributionImpl.cumulativeProbability.
http://commons.apache.org/math/apidocs/org/apache/commons/math/distribution/BetaDistributionImpl.html
To use this class, I must first create a new object with a parameterized
constructor -- BetaDistributionImpl(alpha,beta) and then I can invoke a method.
This two stage process of object instantiation and then method invocation is a
bit clumsy, necessitating a wrapper function.
I would like to be able to specify Pig a pig binding of something like the
following which would allow me to easily declare a binding that performs both
steps without the need for a wrapper.
{code}
register commons-math-2.1.jar;
define (new org.apache.commons.math.distribution.BetaDistributionImpl((double)
alpha, (double) beta)).cumulativeProbability((double) x) BetaIncomplete(x,
alpha, beta)
{code}
What is special about BetaDistributionImpl is that I must first construct an
object instance with parameters of alpha and beta, then I need to invoke the
object method cumulativeProbability to compute my function.
This requires about 100 lines of Java code to create a wrapper just to this one
function instance. And there are something like 1000 functions to bind to.
Better yet, if I could just say something like:
{code}
register commons-math-2.1.jar;
import org.apache.commons.math.distribution.BetaDistributionImpl as BetaDist;
B = foreach A as
alpha,
beta,
x,
BetaDist(alpha,beta).cumulativeProbability(x) as prob;
{code}
Ideally I'd be able to register or include a list of all the bindings to the
library without ever having write another Eval func wrapper.
One question about this proposal is how to handle functions that throw
exceptions such as:
public double cumulativeProbability(double x) throws MathException
I think I would propose that Pig provide a big do something simple in the
declaration:
register commons-math-2.1.jar;
import org.apache.commons.math.distribution.BetaDistributionImpl as BetaDist,
return null on (MathException, Exception);
B = foreach A as
alpha,
beta,
x,
BetaDist(alpha,beta).cumulativeProbability(x) as prob;
{code}
I'm sure if people think about it, there are probably potentially cleaner ways
to import the bindings and handle exceptions cases.
was:
I would like to have a trivial way to bind and invoke Java library functions
from within Pig without creating wrapper functions in Java.
For instance, I need functions out of the Apache Commons Math library
(http://commons.apache.org/math/) such as
BetaDistributionImpl.cumulativeProbability.
http://commons.apache.org/math/apidocs/org/apache/commons/math/distribution/BetaDistributionImpl.html
To use this class, I must first create a new object with a parameterized
constructor -- BetaDistributionImpl(alpha,beta) and then I can invoke a method.
This two stage process of object instantiation and then method invocation is a
bit clumsy, necessitating a wrapper function.
I would like to be able to specify Pig a pig binding of something like the
following which would allow me to easily declare a binding that performs both
steps without the need for a wrapper.
{code}
register commons-math-2.1.jar;
define (new org.apache.commons.math.distribution.BetaDistributionImpl((double)
alpha, (double) beta)).cumulativeProbability((double) x) BetaIncomplete(x,
alpha, beta)
{code}
What is special about BetaDistributionImpl is that I must first construct an
object instance with parameters of alpha and beta, then I need to invoke the
object method cumulativeProbability to compute my function.
This requires about 100 lines of Java code to create a wrapper just to this one
function instance. And there are something like 1000 functions to bind to.
Better yet, if I could just say something like:
{code}
register commons-math-2.1.jar;
import org.apache.commons.math.distribution.BetaDistributionImpl as BetaDist;
B = foreach A as
alpha,
beta,
x,
BetaDist(alpha,beta).cumulativeProbability(x) as prob;
{code}
Ideally I'd be able to register or include a list of all the bindings to the
library without ever having write another Eval func wrapper.
> Need a easy way to bind to external Java library functions that require
> object constructors such as Apache Commons Math library
> -------------------------------------------------------------------------------------------------------------------------------
>
> Key: PIG-1678
> URL: https://issues.apache.org/jira/browse/PIG-1678
> Project: Pig
> Issue Type: New Feature
> Reporter: David Ciemiewicz
>
> I would like to have a trivial way to bind and invoke Java library functions
> from within Pig without creating wrapper functions in Java.
> For instance, I need functions out of the Apache Commons Math library
> (http://commons.apache.org/math/) such as
> BetaDistributionImpl.cumulativeProbability.
>
> http://commons.apache.org/math/apidocs/org/apache/commons/math/distribution/BetaDistributionImpl.html
> To use this class, I must first create a new object with a parameterized
> constructor -- BetaDistributionImpl(alpha,beta) and then I can invoke a
> method. This two stage process of object instantiation and then method
> invocation is a bit clumsy, necessitating a wrapper function.
> I would like to be able to specify Pig a pig binding of something like the
> following which would allow me to easily declare a binding that performs both
> steps without the need for a wrapper.
> {code}
> register commons-math-2.1.jar;
> define (new
> org.apache.commons.math.distribution.BetaDistributionImpl((double) alpha,
> (double) beta)).cumulativeProbability((double) x) BetaIncomplete(x, alpha,
> beta)
> {code}
> What is special about BetaDistributionImpl is that I must first construct an
> object instance with parameters of alpha and beta, then I need to invoke the
> object method cumulativeProbability to compute my function.
> This requires about 100 lines of Java code to create a wrapper just to this
> one function instance. And there are something like 1000 functions to bind
> to.
> Better yet, if I could just say something like:
> {code}
> register commons-math-2.1.jar;
> import org.apache.commons.math.distribution.BetaDistributionImpl as BetaDist;
> B = foreach A as
> alpha,
> beta,
> x,
> BetaDist(alpha,beta).cumulativeProbability(x) as prob;
> {code}
> Ideally I'd be able to register or include a list of all the bindings to the
> library without ever having write another Eval func wrapper.
> One question about this proposal is how to handle functions that throw
> exceptions such as:
> public double cumulativeProbability(double x) throws MathException
> I think I would propose that Pig provide a big do something simple in the
> declaration:
> register commons-math-2.1.jar;
> import org.apache.commons.math.distribution.BetaDistributionImpl as BetaDist,
> return null on (MathException, Exception);
> B = foreach A as
> alpha,
> beta,
> x,
> BetaDist(alpha,beta).cumulativeProbability(x) as prob;
> {code}
> I'm sure if people think about it, there are probably potentially cleaner
> ways to import the bindings and handle exceptions cases.
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