Fix wrong recalculation of slope and speed

Also use a copy for dp and recalculation

simplify.py

@@ -4,6 +4,7 @@ from matplotlib.pyplot import plot, show
 from pylab import polyfit, polyval
 from tkFileDialog import askopenfilename
 from math import pi, sin, sqrt, cos, atan, fabs
+import copy
 
 #-------------------------------------------------------------------------------
 
@@ -38,7 +39,8 @@ class Point:
 
     @staticmethod
     def speed(p1, p2):
-        return p2.segmentlength / (p2.time - p1.time)
+        # don't use segmentlength, it might be outdated. distance is accumulated during loading of the track
+        return (p2.distance - p1.distance) / (p2.time - p1.time)
 
     @staticmethod
     def vspeed(p1, p2):
@@ -46,7 +48,8 @@ class Point:
 
     @staticmethod
     def slope(p1, p2):
-        return (p2.elevation - p1.elevation) / p2.segmentlength
+        # don't use segmentlength, it might be outdated. distance is accumulated during loading of the track
+        return (p2.elevation - p1.elevation) / (p2.distance - p1.distance)
 
     def distanceTo(self, point):
         return Point.distance(self, point)
@@ -169,7 +172,7 @@ if __name__ == "__main__":
     shapename = "result.shp"
 
     track = parseTrack(xml.dom.minidom.parse(gpxname))
-    simplified = dp(track, "distance", "elevation", 5)
+    simplified = dp(copy.deepcopy(track), "distance", "elevation", 5)
     recalculateTrack(simplified)
 
     printTrack(simplified)