cartodb-postgresql/scripts-available/CDB_QuantileBins.sql
2019-05-31 15:37:15 +02:00

19 lines
571 B
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 @extschema@.CDB_QuantileBins(in_array numeric[], breaks int)
RETURNS numeric[]
AS $$
SELECT
percentile_disc(Array(SELECT generate_series(1, breaks) / breaks::numeric))
WITHIN GROUP (ORDER BY x ASC) AS p
FROM
unnest(in_array) AS x;
$$ language SQL IMMUTABLE STRICT PARALLEL SAFE;