Function to add median aggregate to PostgreSQL (requires PL/R)

median.sql

CREATE AGGREGATE public.median(double precision) (
  SFUNC=public.plr_array_accum,
  STYPE=float8[],
  FINALFUNC=r_median
);

CREATE OR REPLACE FUNCTION public.r_median(double precision[])
  RETURNS double precision AS
$BODY$
  median(arg1)
$BODY$ LANGUAGE plr;