naive stddev bins script

stddev_bins.sql

CREATE OR REPLACE FUNCTION CDB_StdDevBins(input numeric[],
                                          num_bins INT DEFAULT 5)
RETURNS NUMERIC[]
AS $$
DECLARE
  mean_val numeric;
  stddev_val numeric;
  out_arr numeric[];
  i int;
BEGIN

  IF array_length(input, 1) <= num_bins
  THEN
    RETURN input;
  END IF;

  SELECT avg(a), stddev(a) INTO mean_val, stddev_val FROM (SELECT unnest(input) as a) x;

  FOR i in 1..(num_bins / 2)
  LOOP
    out_arr := array_append(out_arr, mean_val * i * stddev_val);
  END LOOP;

  RETURN out_arr;

END;
$$ LANGUAGE plpgsql;