do analysis on rescaled coordinates.

this fixes the floating point arithmetic errors that were causing
centroids to be occasionally calculated incorrectly.

output back to geoJSON is still in input coordinate system.

graphs are drawn on rescaled coordinate system, rescaled value is
stored as

Author: brelsford

my_graph.py

@@ -137,12 +137,12 @@ def __ne__(self, other):
     def __hash__(self):
         return hash(self.nodes)
 
-    def geoJSON(self):
+    def geoJSON(self,rezero):
         return {
                    "type": "Feature",
                    "geometry": {
                        "type": "LineString",
-                       "coordinates": [list([n.x, n.y]) for n in self.nodes]
+                       "coordinates": [list([n.x+rezero[0], n.y+rezero[1]]) for n in self.nodes]
                    },
                    "properties": {
                        "road": str(self.road).lower(),
@@ -238,6 +238,7 @@ def __init__(self, G=None, name="S0"):
         self.name = name
         self.cleaned = False
         self.roads_update = True
+        self.rezero_vector = np.array([0,0])
 
         if G is None:
             self.G = nx.Graph()
@@ -283,6 +284,7 @@ def copy(self):
         nx_copy = self.G.copy()
         copy = MyGraph(nx_copy)
         copy.name = self.name
+        copy.rezero_vector = self.rezero_vector
 
         # outerface is a side effect of the creation of inner_facelist
         # so we operate on that in order to not CALL inner_facelist for every
@@ -310,7 +312,7 @@ def inner_facelist(self):
 
     def myedges_geoJSON(self):
         return json.dumps({"type": "FeatureCollection",
-                           "features": [e.geoJSON() for e in self.myedges()]})
+                           "features": [e.geoJSON(self.rezero_vector) for e in self.myedges()]})
 
 
 ############################

my_graph_helpers.py

@@ -928,18 +928,26 @@ def import_and_setup(filename, threshold=1, component=None,
     # check that threshold is a float
 
     sf = shapefile.Reader(filename)
-    myG = graphFromShapes(sf.shapes(), name, rezero)
+    myG1 = graphFromShapes(sf.shapes(), name, rezero)
 
     print("shape file loaded")
 
-    myG = myG.clean_up_geometry(threshold, byblock)
+    myG1 = myG1.clean_up_geometry(threshold, byblock)
 
     print("geometery cleaned up")
 
+    xmin = min([n.x for n in myG1.G.nodes()])
+    ymin = min([n.y for n in myG1.G.nodes()])
+
+    rezero_vector = np.array([xmin, ymin])
+
+    myG2 = rescale_mygraph(myG1, rezero=rezero_vector)
+    myG2.rezero_vector = rezero_vector
+
     if component is None:
-        return myG
+        return myG2
     else:
-        return myG.connected_components()[component]
+        return myG2.connected_components()[component]
 
 
 def rescale_mygraph(myG, rezero=np.array([0, 0]), rescale=np.array([1, 1])):