Yes, it is possible. The UDF should take the percentage you want as a
constructor argument. It will have to be passed as a string and
converted. Then in your Pig Latin, you will use the DEFINE statement
to pass the argument to the constructor.
REGISTER /src/myfunc.jar
DEFINE percentile myfunc.percentile('90');
A = LOAD 'students' as (name, gpa);
B = FOREACH A GENERATE percentile(gpa);
See http://hadoop.apache.org/pig/docs/r0.2.0/piglatin.html#DEFINE for
more details.
Alan.
On May 22, 2009, at 3:37 PM, Brian Long wrote:
Hi,
I'm interested in developing a PERCENTILE UDF, e.g. for calculating a
median, 99th percentile, 90th percentile, etc. I'd like the UDF to be
parametric with respect to the percentile being requested, but I
don't see
any way to do that, and it seems like I might need to create
PERCENTILE_50,
PERCENTILE_90, etc type UDFs explicitly, versus being able to do
something
like GENERATE PERCENTILE(90, duration)
I'm new to Pig, so I might be missing the way to do this... is it
possible?
Thanks,
Brian
