33 lines
1.0 KiB
PL/PgSQL
33 lines
1.0 KiB
PL/PgSQL
--
|
|
-- Determine the Quantile classifications from a numeric array
|
|
--
|
|
-- @param in_array A numeric array of numbers to determine the best
|
|
-- bins based on the Quantile method.
|
|
--
|
|
-- @param breaks The number of bins you want to find.
|
|
--
|
|
--
|
|
CREATE OR REPLACE FUNCTION CDB_QuantileBins ( in_array NUMERIC[], breaks INT) RETURNS NUMERIC[] as $$
|
|
DECLARE
|
|
element_count INT4;
|
|
break_size numeric;
|
|
tmp_val numeric;
|
|
i INT := 1;
|
|
reply numeric[];
|
|
BEGIN
|
|
-- get our unique values
|
|
SELECT array_agg(e) INTO in_array FROM (SELECT unnest(in_array) e GROUP BY e ORDER BY e ASC) x;
|
|
-- get the total size of our row
|
|
element_count := array_length(in_array, 1);
|
|
break_size := element_count::numeric / breaks;
|
|
-- slice our bread
|
|
LOOP
|
|
IF i > breaks THEN EXIT; END IF;
|
|
SELECT e INTO tmp_val FROM ( SELECT unnest(in_array) e LIMIT 1 OFFSET round(break_size * i) - 1) x;
|
|
reply = array_append(reply, tmp_val);
|
|
i := i+1;
|
|
END LOOP;
|
|
RETURN reply;
|
|
END;
|
|
$$ language plpgsql IMMUTABLE;
|