Copy cartodb lib/sql scripts from CDB_CartodbfyTable branch

scripts-available/CDB_QuantileBins.sql

@@ -0,0 +1,32 @@
+--
+-- 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 $$ 
+DECLARE 
+    element_count INT4; 
+    break_size numeric;
+    tmp_val numeric; 
+    i INT := 1; 
+    reply numeric[]; 
+BEGIN 
+    -- get our unique values
+    SELECT array_agg(e) INTO in_array FROM (SELECT unnest(in_array) e GROUP BY e ORDER BY e ASC) x;
+    -- get the total size of our row
+    element_count := array_upper(in_array, 1) - array_lower(in_array, 1); 
+    break_size :=  element_count::numeric / breaks;
+    -- slice our bread
+    LOOP  
+        IF i > breaks THEN  EXIT;  END IF;  
+        SELECT e INTO tmp_val FROM ( SELECT unnest(in_array) e LIMIT 1 OFFSET round(break_size * i)) x;
+        reply = array_append(reply, tmp_val);
+        i := i+1; 
+    END LOOP; 
+    RETURN reply; 
+END; 
+$$ language plpgsql IMMUTABLE;