--- a/python/moving.py	Wed May 20 13:57:47 2015 +0200
+++ b/python/moving.py	Wed May 20 14:21:54 2015 +0200
@@ -1123,6 +1123,22 @@
         else:
             return None
 
+    def getFeatureNumbers(self):
+        '''Returns the number of features at each instant
+        dict instant -> number of features'''
+        if self.hasFeatures():
+            featureNumbers = {}
+            for t in self.getTimeInterval():
+                n = 0
+                for f in self.getFeatures():
+                    if f.existsAtInstant(t):
+                        n += 1
+                featureNumbers[t]=n
+            return featureNumbers
+        else:
+            print('Object {} has no features loaded.'.format(self.getNum()))
+            return None
+
     def getSpeeds(self):
         return self.getVelocities().norm()