add example for using node cache

Author: lonvia

examples/use_nodecache.py

@@ -0,0 +1,30 @@
+import osmium as o
+import sys
+
+class WayHandler(o.SimpleHandler):
+
+    def __init__(self, idx):
+        o.SimpleHandler.__init__(self)
+        self.idx = idx
+
+    def way(self, w):
+        for n in w.nodes:
+            n.lat, n.lon # throws an exception if the coordinates are missing
+            loc = idx.get(n.ref)
+        print w.id, len(w.nodes)
+
+if len(sys.argv) != 3:
+    print "Usage: python create_nodecache.py <osm file> <node cache>"
+    exit()
+
+reader = o.io.Reader(sys.argv[1], o.osm.osm_entity_bits.WAY)
+
+idxfile = open(sys.argv[2], 'a+b')
+print sys.argv[2],idxfile.fileno()
+
+idx = o.index.DenseLocationMapFile(idxfile.fileno())
+lh = o.NodeLocationsForWays(idx)
+
+o.apply(reader, lh, WayHandler(idx))
+
+reader.close()

lib/osm.cc

@@ -62,6 +62,7 @@ BOOST_PYTHON_MODULE(_osm)
         .add_property("lon", &osmium::NodeRef::lon)
         .add_property("lat", &osmium::NodeRef::lat)
         .add_property("ref", &osmium::NodeRef::ref)
+        .add_property("location", static_cast<osmium::Location (osmium::NodeRef::*)() const>(&osmium::NodeRef::location))
     ;
     class_<osmium::WayNodeList, boost::noncopyable>("WayNodeList", no_init)
         .def("__len__", &osmium::WayNodeList::size)

lib/osmium.cc

@@ -57,4 +57,5 @@ BOOST_PYTHON_MODULE(_osmium)
     def("apply", &apply_reader_simple<VirtualHandler>);
     def("apply", &apply_reader_simple<osmium::handler::NodeLocationsForWays<DenseLocationMapFile>>);
     def("apply", &apply_reader_simple_with_location<SparseLocationTable>);
+    def("apply", &apply_reader_simple_with_location<DenseLocationMapFile>);
 }