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https://issues.apache.org/jira/browse/PIG-1385?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=12859568#action_12859568
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Alan Gates commented on PIG-1385:
---------------------------------
Functions look good. Javadoc on how the functions should be used (what input
they expect and what output they'll produce) should be added so that users can
see how to use the functions.
> UDF to create tuples and bags
> -----------------------------
>
> Key: PIG-1385
> URL: https://issues.apache.org/jira/browse/PIG-1385
> Project: Pig
> Issue Type: New Feature
> Components: tools
> Affects Versions: 0.6.0
> Reporter: hc busy
> Attachments: PIG-1385-trunk.patch
>
> Original Estimate: 24h
> Remaining Estimate: 24h
>
> Based on this conversation:
> > On Tue, Apr 20, 2010 at 6:34 PM, hc busy <hc.b...@gmail.com> wrote:
> >
> > > What about making them part of the language using symbols?
> > >
> > > instead of
> > >
> > > foreach T generate Tuple($0, $1, $2), Bag($3, $4, $5), $6, $7;
> > >
> > > have language support
> > >
> > > foreach T generate ($0, $1, $2), {$3, $4, $5}, $6, $7;
> > >
> > > or even:
> > >
> > > foreach T generate ($0, $1, $2), {$3, $4, $5}, [$6#$7, $8#$9], $10, $11;
> > >
> > >
> > > Is there reason not to do the second or third other than being more
> > > complicated?
> > >
> > > Certainly I'd volunteer to put the top implementation in to the util
> > > package and submit them for builtin's, but the latter syntactic candies
> > > seems more natural..
> > >
> > >
> > >
> > > On Tue, Apr 20, 2010 at 5:24 PM, Alan Gates <ga...@yahoo-inc.com> wrote:
> > >
> > >> The grouping package in piggybank is left over from back when Pig
> > allowed
> > >> users to define grouping functions (0.1). Functions like these should
> > go in
> > >> evaluation.util.
> > >>
> > >> However, I'd consider putting these in builtin (in main Pig) instead.
> > >> These are things everyone asks for and they seem like a reasonable
> > addition
> > >> to the core engine. This will be more of a burden to write (as we'll
> > hold
> > >> them to a higher standard) but of more use to people as well.
> > >>
> > >> Alan.
> > >>
> > >>
> > >> On Apr 19, 2010, at 12:53 PM, hc busy wrote:
> > >>
> > >> Some times I wonder... I mean, somebody went to the trouble of making a
> > >>> path
> > >>> called
> > >>>
> > >>> org.apache.pig.piggybank.grouping
> > >>>
> > >>> (where it seems like this code belong), but didn't check in any java
> > code
> > >>> into that package.
> > >>>
> > >>>
> > >>> Any comment about where to put this kind of utility classes?
> > >>>
> > >>>
> > >>>
> > >>> On Mon, Apr 19, 2010 at 12:07 PM, Andrey S <oct...@gmail.com> wrote:
> > >>>
> > >>> 2010/4/19 hc busy <hc.b...@gmail.com>
> > >>>>
> > >>>> That's just the way it is right now, you can't make bags or tuples
> > >>>>> directly... Maybe we should have some UDF's in piggybank for these:
> > >>>>>
> > >>>>> toBag()
> > >>>>> toTuple(); --which is kinda like exec(Tuple in){return in;}
> > >>>>> TupleToBag(); --some times you need it this way for some reason.
> > >>>>>
> > >>>>>
> > >>>>> Ok. I place my current code here, may be later I make a patch (if
> > such
> > >>>> implementation is acceptable of course).
> > >>>>
> > >>>> import org.apache.pig.EvalFunc;
> > >>>> import org.apache.pig.data.BagFactory;
> > >>>> import org.apache.pig.data.DataBag;
> > >>>> import org.apache.pig.data.Tuple;
> > >>>> import org.apache.pig.data.TupleFactory;
> > >>>>
> > >>>> import java.io.IOException;
> > >>>>
> > >>>> /**
> > >>>> * Convert any sequence of fields to bag with specified count of
> > >>>> fields<br>
> > >>>> * Schema: count:int, fld1 [, fld2, fld3, fld4... ].
> > >>>> * Output: count=2, then { (fld1, fld2) , (fld3, fld4) ... }
> > >>>> *
> > >>>> * @author astepachev
> > >>>> */
> > >>>> public class ToBag extends EvalFunc<DataBag> {
> > >>>> public BagFactory bagFactory;
> > >>>> public TupleFactory tupleFactory;
> > >>>>
> > >>>> public ToBag() {
> > >>>> bagFactory = BagFactory.getInstance();
> > >>>> tupleFactory = TupleFactory.getInstance();
> > >>>> }
> > >>>>
> > >>>> @Override
> > >>>> public DataBag exec(Tuple input) throws IOException {
> > >>>> if (input.isNull())
> > >>>> return null;
> > >>>> final DataBag bag = bagFactory.newDefaultBag();
> > >>>> final Integer couter = (Integer) input.get(0);
> > >>>> if (couter == null)
> > >>>> return null;
> > >>>> Tuple tuple = tupleFactory.newTuple();
> > >>>> for (int i = 0; i < input.size() - 1; i++) {
> > >>>> if (i % couter == 0) {
> > >>>> tuple = tupleFactory.newTuple();
> > >>>> bag.add(tuple);
> > >>>> }
> > >>>> tuple.append(input.get(i + 1));
> > >>>> }
> > >>>> return bag;
> > >>>> }
> > >>>> }
> > >>>>
> > >>>> import org.apache.pig.ExecType;
> > >>>> import org.apache.pig.PigServer;
> > >>>> import org.junit.Before;
> > >>>> import org.junit.Test;
> > >>>>
> > >>>> import java.io.IOException;
> > >>>> import java.net.URISyntaxException;
> > >>>> import java.net.URL;
> > >>>>
> > >>>> import static org.junit.Assert.assertTrue;
> > >>>>
> > >>>> /**
> > >>>> * @author astepachev
> > >>>> */
> > >>>> public class ToBagTest {
> > >>>> PigServer pigServer;
> > >>>> URL inputTxt;
> > >>>>
> > >>>> @Before
> > >>>> public void init() throws IOException, URISyntaxException {
> > >>>> pigServer = new PigServer(ExecType.LOCAL);
> > >>>> inputTxt =
> > >>>> this.getClass().getResource("bagTest.txt").toURI().toURL();
> > >>>> }
> > >>>>
> > >>>> @Test
> > >>>> public void testSimple() throws IOException {
> > >>>> pigServer.registerQuery("a = load '" + inputTxt.toExternalForm()
> > +
> > >>>> "' using PigStorage(',') " +
> > >>>> "as (id:int, a:chararray, b:chararray, c:chararray,
> > >>>> d:chararray);");
> > >>>> pigServer.registerQuery("last = foreach a generate flatten(" +
> > >>>> ToBag.class.getName() + "(2, id, a, id, b, id, c));");
> > >>>>
> > >>>> pigServer.deleteFile("target/pigtest/func1.txt");
> > >>>> pigServer.store("last", "target/pigtest/func1.txt");
> > >>>> assertTrue(pigServer.fileSize("target/pigtest/func1.txt") > 0);
> > >>>> }
> > >>>> }
> > >>>>
> > >>>>
> > >>
> > >
> >
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