Pig 0.12 Nested Foreach not working properly - filter

Question

I've been trying to do this for a while and can't seem to figure it out and it's a bit hard to look for a fix for my problem.
I have a relation that I previously grouped by user_id and listing_id and after generating and flattened the output I got this:
test: {user_id: bytearray,listing_id: bytearray,hotness: long}
So my next step is to group by user, order by hotness and limit the amount of listings per user to 20.
grped = GROUP test BY user_id;
grped_sorted = FOREACH grped {
sorted = order test BY hotness desc;
top1 = limit sorted 20;
listings = FOREACH top1 GENERATE FLATTEN((bytearray)top1.listing_id) as listing_id;
GENERATE group as user_id, FLATTEN(listings.($0)) as listing_ids;
};
But this seems to be getting me the error, with information that was previously stripped from the listings details:
Scalar has more than one row in the output.
Please, I need help on this.
Is there a way to do this? Can I use some UDF from DataFu?
Creating my own UDF is out of the question.
Thanks in advance.

Answer 1

I think it should work if the code looks like this
grped = GROUP test BY user_id;
grped_sorted = FOREACH grped {
sorted = order test BY hotness desc;
top1 = limit sorted 20;
GENERATE group as user_id, top1.listing_id as listing_ids;
};
Output of this would be something like
grped_sorted: {user_id: bytearray,listing_ids: {(listing_id: bytearray)}}
Not sure if this is what you want though.