I am trying to use an EVAL pig function (it's called BagSplit from datafu)
which accepts a Bag as a parameter.

The problem I have is that my current relation is a single Bag, so I'm not
sure how to pass this relation to the Eval function.

My pig script looks like this:

F = FOREACH E GENERATE $0,$1;

DESCRIBE F;

F: {id: chararray,countd: long}

G = FOREACH F GENERATE BagSplit(??);

Not sure what I can put in ??

Thanks,
James

Howdy James. It's important to remember that relations and bags are not the
same (though they feel pretty similar). EvalFuncs can never be run directly
on a relation, only on a bag. In this case, you need to group first.

-- F: {id: chararray,countd: long}

G = group F all;

H = FOREACH G GENERATE BagSplit(F);

"group all" is what lets you effectively turn a relation directly into a
bag. describe G and you'll see that now you have a relation of one row,
where that row is the catchall key "all," and then a bag named "F" that is
the relation you wanted to run BagSplit on.

2012/5/28 James Newhaven <[EMAIL PROTECTED]>

> I am trying to use an EVAL pig function (it's called BagSplit from datafu)
> which accepts a Bag as a parameter.
>
> The problem I have is that my current relation is a single Bag, so I'm not
> sure how to pass this relation to the Eval function.
>
> My pig script looks like this:
>
> F = FOREACH E GENERATE $0,$1;
>
> DESCRIBE F;
>
> F: {id: chararray,countd: long}
>
> G = FOREACH F GENERATE BagSplit(??);
>
> Not sure what I can put in ??
>
> Thanks,
> James
>

Thanks Jonathan. Great explanation.

On Mon, May 28, 2012 at 6:53 PM, Jonathan Coveney <[EMAIL PROTECTED]>wrote:

> Howdy James. It's important to remember that relations and bags are not the
> same (though they feel pretty similar). EvalFuncs can never be run directly
> on a relation, only on a bag. In this case, you need to group first.
>
> -- F: {id: chararray,countd: long}
>
> G = group F all;
>
> H = FOREACH G GENERATE BagSplit(F);
>
> "group all" is what lets you effectively turn a relation directly into a
> bag. describe G and you'll see that now you have a relation of one row,
> where that row is the catchall key "all," and then a bag named "F" that is
> the relation you wanted to run BagSplit on.
>
> 2012/5/28 James Newhaven <[EMAIL PROTECTED]>
>
> > I am trying to use an EVAL pig function (it's called BagSplit from
> datafu)
> > which accepts a Bag as a parameter.
> >
> > The problem I have is that my current relation is a single Bag, so I'm
> not
> > sure how to pass this relation to the Eval function.
> >
> > My pig script looks like this:
> >
> > F = FOREACH E GENERATE $0,$1;
> >
> > DESCRIBE F;
> >
> > F: {id: chararray,countd: long}
> >
> > G = FOREACH F GENERATE BagSplit(??);
> >
> > Not sure what I can put in ??
> >
> > Thanks,
> > James
> >
>