KMeans clustering and weighted centroid analysis

src/pg/sql/11_kmeans.sql

@@ -0,0 +1,31 @@
+CREATE OR REPLACE FUNCTION  CDB_KMeans(query text, no_clusters integer,no_init integer default 20)
+RETURNS table (cartodb_id integer, cluster_no integer) as $$
+    
+    import plpy 
+    plpy.execute('SELECT cdb_crankshaft._cdb_crankshaft_activate_py()')
+    from crankshaft.clustering import kmeans
+    return kmeans(query,no_clusters,no_init)
+
+$$ language plpythonu;
+
+CREATE OR REPLACE FUNCTION CDB_WeightedMean(query text, weight_column text, category_column text default null )
+RETURNS table (the_geom geometry,class integer ) as $$
+BEGIN
+
+RETURN QUERY
+    EXECUTE format( $string$
+        select ST_SETSRID(st_makepoint(cx, cy),4326) the_geom, class  from (
+            select  
+                   %I as class,
+                   sum(st_x(the_geom)*%I)/sum(%I) cx,
+                   sum(st_y(the_geom)*%I)/sum(%I) cy
+                   from (%s) a
+                   group by %I
+            ) q          
+     
+        $string$, category_column, weight_column,weight_column,weight_column,weight_column,query, category_column 
+    )
+    using the_geom
+    RETURN;
+END 
+$$ LANGUAGE plpgsql;