Changeset 4847

Timestamp:

11/17/09 12:03:50 (2 years ago)

Author:

pramsey

Message:

Implement ST_CollectionExtract() to pull specific homogeneous collections out of heterogeneous collections. Regressions and documentation included. (#218)

Location:

trunk

Files:

• doc/reference_editor.xml (modified) (1 diff)
• liblwgeom/cunit/cu_libgeom.c (modified) (2 diffs)
• liblwgeom/cunit/cu_libgeom.h (modified) (1 diff)
• liblwgeom/liblwgeom.h (modified) (1 diff)
• liblwgeom/lwcollection.c (modified) (1 diff)
• liblwgeom/lwutil.c (modified) (1 diff)
• postgis/lwgeom_functions_basic.c (modified) (2 diffs)
• postgis/postgis.sql.in.c (modified) (1 diff)
• regress/regress_expected (modified) (1 diff)
• regress/regress.sql (modified) (1 diff)

trunk/doc/reference_editor.xml

@@ -606 +606 @@
         </refentry>
 
+        <refentry id="ST_CollectionExtract">
+                <refnamediv>
+                        <refname>ST_CollectionExtract</refname>
+
+                        <refpurpose>Given a GEOMETRYCOLLECTION, returns the a MULTI* geometry consisting only the specified type. Sub-geometries that are not
+                            the specified type are ignored.</refpurpose>
+                </refnamediv>
+
+                <refsynopsisdiv>
+                        <funcsynopsis>
+                          <funcprototype>
+                                <funcdef>geometry <function>ST_CollectionExtract</function></funcdef>
+                                <paramdef><type>geometry </type> <parameter>collection</parameter></paramdef>
+                                <paramdef><type>integer </type> <parameter>type</parameter></paramdef>
+                          </funcprototype>
+                        </funcsynopsis>
+                </refsynopsisdiv>
+
+                <refsection>
+                        <title>Description</title>
+
+                        <para>Given a GEOMETRYCOLLECTION, returns the a MULTI* geometry consisting only the specified type. Sub-geometries that are not
+                            the specified type are ignored. If there are no sub-geometries of the right type, an EMPTY collection will be returned. Only
+                            points, lines and polygons are supported.</para>
+
+                </refsection>
+
+                <refsection>
+                        <title>Examples</title>
+
+                        <programlisting>SELECT ST_AsText(ST_CollectionExtract(ST_GeomFromText('GEOMETRYCOLLECTION(GEOMETRYCOLLECTION(POINT(0 0)))'),1));
+                        st_astext
+                        ---------------
+                        MULTIPOINT(0 0)
+                        (1 row)
+                        </programlisting>
+                </refsection>
+                <refsection>
+                        <title>See Also</title>
+                        <para><xref linkend="ST_Multi" /></para>
+                </refsection>
+        </refentry>
+        
         <refentry id="ST_Multi">
                 <refnamediv>

trunk/liblwgeom/cunit/cu_libgeom.c

@@ -38 +38 @@
             (NULL == CU_add_test(pSuite, "test_lwgeom_count_vertices()", test_lwgeom_count_vertices))  || 
             (NULL == CU_add_test(pSuite, "test_on_gser_lwgeom_count_vertices()", test_on_gser_lwgeom_count_vertices))  ||
-            (NULL == CU_add_test(pSuite, "test_gbox_calculation()", test_gbox_calculation))  
+            (NULL == CU_add_test(pSuite, "test_gbox_calculation()", test_gbox_calculation)) ||
+            (NULL == CU_add_test(pSuite, "test_lwcollection_extract()", test_lwcollection_extract))  
 
         )
@@ -458 +459 @@
         lwfree(gbox);
 }
+
+void test_lwcollection_extract(void)
+{
+
+        LWGEOM *geom;
+        LWCOLLECTION *col;
+        
+        geom = lwgeom_from_ewkt("GEOMETRYCOLLECTION(POINT(0 0))", PARSER_CHECK_NONE);
+        col = lwcollection_extract((LWCOLLECTION*)geom, 1);
+        CU_ASSERT_EQUAL(TYPE_GETTYPE(col->type), MULTIPOINTTYPE);
+
+        lwcollection_release(col);
+        lwgeom_free(geom);
+        
+}

trunk/liblwgeom/cunit/cu_libgeom.h

@@ -38 +38 @@
 void test_gbox_serialized_size(void);
 void test_gbox_calculation(void);
+void test_lwcollection_extract(void);

trunk/liblwgeom/liblwgeom.h

@@ -917 +917 @@
 LWGEOM *lwcollection_getsubgeom(LWCOLLECTION *col, int gnum);
 BOX3D *lwcollection_compute_box3d(LWCOLLECTION *col);
-
+LWCOLLECTION* lwcollection_extract(LWCOLLECTION *col, int type);
 
 /******************************************************************

trunk/liblwgeom/lwcollection.c

@@ -558 +558 @@
         return boxfinal;
 }
+
+/**
+* Takes a potentially heterogeneous collection and returns a homogeneous
+* collection consisting only of the specified type.
+*/
+LWCOLLECTION* lwcollection_extract(LWCOLLECTION *col, int type)
+{
+        int i = 0;
+        LWGEOM **geomlist;
+        BOX3D *b3d;
+        LWCOLLECTION *outcol;
+        int geomlistsize = 16;
+        int geomlistlen = 0;
+        uchar outtype;
+
+        if( ! col ) return NULL;
+
+        switch (type)
+        {
+                case POINTTYPE:
+                        outtype = MULTIPOINTTYPE;
+                        break;
+                case LINETYPE:
+                        outtype = MULTILINETYPE;
+                        break;
+                case POLYGONTYPE:
+                        outtype = MULTIPOLYGONTYPE;
+                        break;
+                default:
+                        lwerror("Only POLYGON, LINESTRING and POINT are supported by lwcollection_extract. %s requested.", lwgeom_typename(type));
+                        return NULL;
+        }
+        
+        geomlist = lwalloc(sizeof(LWGEOM*) * geomlistsize);
+
+        /* Process each sub-geometry */
+        for( i = 0; i < col->ngeoms; i++ )
+        {
+                int subtype = TYPE_GETTYPE(col->geoms[i]->type);
+                /* Copy our sub-types into the output list */
+                if( subtype == type )
+                {
+                        /* We've over-run our buffer, double the memory segment */
+                        if( geomlistlen == geomlistsize )
+                        {
+                                geomlistsize *= 2;
+                                geomlist = lwrealloc(geomlist, sizeof(LWGEOM*) * geomlistsize);
+                        }
+                        geomlist[geomlistlen] = col->geoms[i];
+                        geomlistlen++;
+                }
+                if( lwgeom_is_collection( subtype ) )
+                {
+                        int j = 0;
+                        LWCOLLECTION *tmpcol = lwcollection_extract((LWCOLLECTION*)col->geoms[i], type);
+                        for( j = 0; j < tmpcol->ngeoms; j++ )
+                        {
+                                /* We've over-run our buffer, double the memory segment */
+                                if( geomlistlen == geomlistsize )
+                                {
+                                        geomlistsize *= 2;
+                                        geomlist = lwrealloc(geomlist, sizeof(LWGEOM*) * geomlistsize);
+                                }
+                                geomlist[geomlistlen] = tmpcol->geoms[j];
+                                geomlistlen++;
+                        }
+                        lwfree(tmpcol);
+                }
+        }
+        
+        if( geomlistlen > 0 )
+        {
+                outcol = lwcollection_construct(outtype, col->SRID, NULL, geomlistlen, geomlist);       
+                b3d = lwcollection_compute_box3d(outcol);
+                outcol->bbox = box3d_to_box2df(b3d);
+        }
+        else
+        {
+                outcol = lwcollection_construct_empty(col->SRID, TYPE_HASZ(col->type), TYPE_HASM(col->type));
+        }
+        
+        return outcol;
+}
+

trunk/liblwgeom/lwutil.c

@@ -208 +208 @@
 
 
-const char *
-lwgeom_typename(int type)
+const char* lwgeom_typename(int type)
 {
         /* something went wrong somewhere */

trunk/postgis/lwgeom_functions_basic.c

@@ -79 +79 @@
 Datum ST_GeoHash(PG_FUNCTION_ARGS);
 Datum ST_MakeEnvelope(PG_FUNCTION_ARGS);
+Datum ST_CollectionExtract(PG_FUNCTION_ARGS);
 
 void lwgeom_affine_ptarray(POINTARRAY *pa, double afac, double bfac, double cfac,
@@ -3436 +3437 @@
 
 }
+
+PG_FUNCTION_INFO_V1(ST_CollectionExtract);
+Datum ST_CollectionExtract(PG_FUNCTION_ARGS)
+{
+        PG_LWGEOM *input = (PG_LWGEOM *)PG_DETOAST_DATUM(PG_GETARG_DATUM(0));
+        PG_LWGEOM *output;
+        LWGEOM *lwgeom = pglwgeom_deserialize(input);
+        LWCOLLECTION *lwcol = NULL;
+        int type = PG_GETARG_INT32(1);
+        int lwgeom_type = TYPE_GETTYPE(lwgeom->type);
+        
+        /* Ensure the right type was input */
+        if ( ! ( type == POINTTYPE || type == LINETYPE || type == POLYGONTYPE ) )
+        {
+                lwgeom_free(lwgeom);
+                elog(ERROR, "ST_CollectionExtract: only point, linestring and polygon may be extracted");
+                PG_RETURN_NULL();
+        }
+        
+        /* Mirror non-collections right back */
+        if ( ! lwgeom_is_collection(lwgeom_type) )
+        {
+                output = palloc(VARSIZE(input));
+                memcpy(VARDATA(output), VARDATA(input), VARSIZE(input) - VARHDRSZ);
+                SET_VARSIZE(output, VARSIZE(input));
+                lwgeom_free(lwgeom);
+                PG_RETURN_POINTER(output);
+        }
+
+        lwcol = lwcollection_extract((LWCOLLECTION*)lwgeom, type);
+        output = pglwgeom_serialize((LWGEOM*)lwcol);
+        lwgeom_free(lwgeom); 
+
+        PG_RETURN_POINTER(output);
+}

trunk/postgis/postgis.sql.in.c

@@ -1437 +1437 @@
         RETURNS geometry
         AS 'MODULE_PATHNAME', 'LWGEOM_force_collection'
+        LANGUAGE 'C' IMMUTABLE STRICT;
+
+-- Availability: 1.5.0
+CREATE OR REPLACE FUNCTION ST_CollectionExtract(geometry, integer)
+        RETURNS geometry
+        AS 'MODULE_PATHNAME', 'ST_CollectionExtract'
         LANGUAGE 'C' IMMUTABLE STRICT;
 

trunk/regress/regress_expected

@@ -198 +198 @@
 151|0103000020E61000000100000005000000000000000000000000000000000000000000000000000000000000000000F03F000000000000F03F000000000000F03F000000000000F03F000000000000000000000000000000000000000000000000
 152|4326
+153|MULTIPOINT(0 0)
+154|MULTIPOINT(0 0)
+155|MULTIPOINT(0 0,1 1)
+156|MULTIPOINT(1 1)
+157|MULTILINESTRING((0 0,1 1))
+158|MULTILINESTRING((0 0,1 1),(2 2,3 3))
+159|GEOMETRYCOLLECTION EMPTY
+160|MULTIPOINT(1 1)
+161|MULTILINESTRING((0 0,1 1),(2 2,3 3))

trunk/regress/regress.sql

@@ -278 +278 @@
 select '152', ST_SRID(ST_MakeEnvelope(0, 0, 1, 1, 4326));
 
+select '153', ST_AsText(ST_CollectionExtract('GEOMETRYCOLLECTION(POINT(0 0))',1));
+select '154', ST_AsText(ST_CollectionExtract('GEOMETRYCOLLECTION(GEOMETRYCOLLECTION(POINT(0 0)))',1));
+select '155', ST_AsText(ST_CollectionExtract('GEOMETRYCOLLECTION(GEOMETRYCOLLECTION(POINT(0 0), POINT(1 1)))',1));
+select '156', ST_AsText(ST_CollectionExtract('GEOMETRYCOLLECTION(GEOMETRYCOLLECTION(LINESTRING(0 0, 1 1), POINT(1 1)))',1));
+select '157', ST_AsText(ST_CollectionExtract('GEOMETRYCOLLECTION(GEOMETRYCOLLECTION(LINESTRING(0 0, 1 1), POINT(1 1)))',2));
+select '158', ST_AsText(ST_CollectionExtract('GEOMETRYCOLLECTION(GEOMETRYCOLLECTION(LINESTRING(0 0, 1 1), POINT(1 1)),LINESTRING(2 2, 3 3))',2));
+select '159', ST_AsText(ST_CollectionExtract('GEOMETRYCOLLECTION(GEOMETRYCOLLECTION(LINESTRING(0 0, 1 1), POINT(1 1)),LINESTRING(2 2, 3 3))',3));
+select '160', ST_AsText(ST_CollectionExtract('GEOMETRYCOLLECTION(GEOMETRYCOLLECTION(LINESTRING(0 0, 1 1), POINT(1 1)),LINESTRING(2 2, 3 3))',1));
+select '161', ST_AsText(ST_CollectionExtract('GEOMETRYCOLLECTION(GEOMETRYCOLLECTION(LINESTRING(0 0, 1 1), GEOMETRYCOLLECTION(POINT(1 1))),LINESTRING(2 2, 3 3))',2));
+
 
 -- Drop test table