sql

lib/sql/scripts-available/CDB_QuantileBins.sql

@@ -0,0 +1,18 @@
+--
+-- 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;