[ https://issues.apache.org/jira/browse/PIG1678?page=com.atlassian.jira.plugin.system.issuetabpanels:alltabpanel
]
David Ciemiewicz updated PIG1678:

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 commonsmath2.1.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 commonsmath2.1.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 commonsmath2.1.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 commonsmath2.1.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 commonsmath2.1.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: PIG1678
> URL: https://issues.apache.org/jira/browse/PIG1678
> 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 commonsmath2.1.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 commonsmath2.1.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 commonsmath2.1.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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