--- a/python/moving.py	Fri May 25 14:23:56 2018 -0400
+++ b/python/moving.py	Fri May 25 15:14:27 2018 -0400
@@ -1143,7 +1143,106 @@
         return MovingObject(num = num, timeInterval = timeInterval, positions = positions, velocities = velocities)
 
     @staticmethod
-    def concatenate(obj1, obj2, num = None, computePositions = False):
+    def concatenateWith(obj1, ObjectList=[], num = None): #Concatenate with a list of MovingObjects
+    	if len(ObjectList)==0:
+    		newObject = MovingObject(obj1.getNum() if num is None else num, obj1.getTimeInterval(), obj1.positions, obj1.velocities, userType = obj1.getUserType())
+    		if obj1.hasFeatures() :
+    			newObject.features = list(obj1.features)
+    	else:
+    		def getKey(item):
+    			return 0 if not obj1.commonTimeInterval(item).empty() else max(obj1.getFirstInstant(),item.getFirstInstant())-min(obj1.getLastInstant(),item.getLastInstant())
+    		Order = min(ObjectList , key=getKey)
+    		newObject = MovingObject.concatenate(obj1, Order, num)
+    		ObjectList.remove(Order)
+    		newObject = MovingObject.concatenateWith(newObject,ObjectList)
+    	return newObject
+
+    @staticmethod
+    def addFeatures(obj1, FeatureList=[], num = None): #Add features to an object
+    	if len(FeatureList)==0: #We return a clone
+    		newObject = MovingObject(obj1.getNum() if num is None else num, obj1.getTimeInterval(), obj1.positions, obj1.velocities, userType = obj1.getUserType()) 
+    		if obj1.features is not None:
+    			newObject.features = list(obj1.features)
+	else :
+		newObjectTMP = MovingObject.concatenateWith(obj1,FeatureList,num)
+		newObject = MovingObject(newObjectTMP.getNum() if num is None else num, newObjectTMP.getTimeInterval(), newObjectTMP.positions, newObjectTMP.velocities, userType = newObjectTMP.getUserType())
+		if obj1.hasFeatures() and newObjectTMP.hasFeatures():
+			newObject.features = obj1.features + newObjectTMP.features
+		
+	return newObject
+	
+
+    @staticmethod
+    def delFeatures(obj1, FeatureList=[], num = None):
+    	if obj1.features is not None:
+    		if len(FeatureList)>0:
+    			tmp = [ i for i in obj1.features and i not in FeatureList]
+    			if len(obj1.features)!=len(tmp):
+    				newInterval = TimeInterval(min([i.getFirstInstant() for i in tmp]), max([i.getLastInstant() for i in tmp]))
+		    		positions = Trajectory()
+		    		for t in newInterval:
+					nTotal = 0.
+					p = Point(0.,0.)
+					for obj in tmp:
+					    if obj.existsAtInstant(t):
+						if obj.hasFeatures():
+						    n = len([f for f in obj.getFeatures() if f.existsAtInstant(t)])
+						else:
+						    n = 1.
+						p += obj.getPositionAtInstant(t).__mul__(n)
+						nTotal += n
+					if nTotal==0:
+						positions.addPosition(obj1.getPositionAtInstant(t))
+					else:
+						positions.addPosition(p.divide(nTotal))
+				if hasattr(obj1, 'velocities'):
+					velocities = Trajectory()
+					for t in newTimeInterval:
+						nTotal = 0.
+						p = Point(0.,0.)
+						for obj in tmp:
+							if obj.existsAtInstant(t):
+							    if obj.hasFeatures():
+								n = len([f for f in obj.getFeatures() if f.existsAtInstant(t)])
+							    else:
+								n = 1.
+							    p += obj.getVelocityAtInstant(t).__mul__(n)
+							    nTotal += n
+						if nTotal==0:
+							velocities.addPosition(obj1.getVelocityAtInstant(t))
+						else:
+							velocities.addPosition(p.divide(nTotal))
+				else:
+					velocities = None
+				
+				newObject = MovingObject(obj1.getNum() if num is None else num, newInterval, positions, velocities, userType = obj1.getUserType())
+				newObject.features = tmp+[MovingObject(obj1.getNum() if num is None else num, newInterval, positions, velocities, userType = obj1.getUserType())]
+    	else:
+    		newObject = MovingObject(obj1.getNum() if num is None else num, obj1.getTimeInterval(), obj1.positions, obj1.velocities, userType = obj1.getUserType())
+    	return newObject
+		
+
+    def updatePosition(self):
+    	if self.features is not None:
+    		print 'On update ici'
+	    	positions = Trajectory()
+	    	for t in self.getTimeInterval():
+	    		nTotal = 0.
+			p = Point(0.,0.)
+			for obj in self.features:
+				if obj.existsAtInstant(t):
+					if obj.hasFeatures():
+						n = len([f for f in obj.getFeatures() if f.existsAtInstant(t)])
+					else:
+						n = 1.
+					p += obj.getPositionAtInstant(t).__mul__(n)
+					nTotal += n
+			assert nTotal>0, 'there should be at least one point for each instant'
+                	positions.addPosition(p.divide(nTotal))
+                self.positions = positions
+
+    @staticmethod
+    def concatenate(obj1, obj2, num = None):
         '''Concatenates two objects supposed to overlap temporally '''
 	if num is None:
 		newNum = obj1.getNum()
@@ -1171,14 +1270,30 @@
             	py+=vitessey
 
 	    newObject = MovingObject(newNum, emptyInterval, positions, velocities, userType = obj1.getUserType())
+	    newObject.features = [MovingObject(newNum, emptyInterval, positions, velocities, userType = obj1.getUserType())] #In case there is features to add when we recursively call concatenate 
             return MovingObject.concatenate(MovingObject.concatenate(obj1, newObject),obj2)
             
             
         else:
             newTimeInterval = TimeInterval.union(obj1.getTimeInterval(), obj2.getTimeInterval())
             # positions
-            if computePositions: # TODO it would probably be better to recompute from all features, if features are available, in other method
-                positions = Trajectory()
+            positions = Trajectory()
+            for t in newTimeInterval:
+                nTotal = 0.
+                p = Point(0.,0.)
+                for obj in [obj1, obj2]:
+                    if obj.existsAtInstant(t):
+                        if obj.hasFeatures():
+                            n = len([f for f in obj.getFeatures() if f.existsAtInstant(t)])
+                        else:
+                            n = 1.
+                        p += obj.getPositionAtInstant(t).__mul__(n)
+                        nTotal += n
+                assert nTotal>0, 'there should be at least one point for each instant'
+                positions.addPosition(p.divide(nTotal))
+            # velocities: if any
+            if hasattr(obj1, 'velocities') and hasattr(obj2, 'velocities'):
+                velocities = Trajectory()
                 for t in newTimeInterval:
                     nTotal = 0.
                     p = Point(0.,0.)
@@ -1188,30 +1303,11 @@
                                 n = len([f for f in obj.getFeatures() if f.existsAtInstant(t)])
                             else:
                                 n = 1.
-                            p += obj.getPositionAtInstant(t).__mul__(n)
+                            p += obj.getVelocityAtInstant(t).__mul__(n)
                             nTotal += n
                     assert nTotal>0, 'there should be at least one point for each instant'
-                    positions.addPosition(p.divide(nTotal))
-                # velocities: if any
-                if obj1.getVelocities() is not None and obj2.getVelocities() is not None:
-                    velocities = Trajectory()
-                    for t in newTimeInterval:
-                        nTotal = 0.
-                        p = Point(0.,0.)
-                        for obj in [obj1, obj2]:
-                            if obj.existsAtInstant(t):
-                                if obj.hasFeatures():
-                                    n = len([f for f in obj.getFeatures() if f.existsAtInstant(t)])
-                                else:
-                                    n = 1.
-                                p += obj.getVelocityAtInstant(t).__mul__(n)
-                                nTotal += n
-                        assert n>0, 'there should be at least one point for each instant'
-                        velocities.addPosition(p.divide(nTotal))
-                else:
-                    velocities = None
+                    velocities.addPosition(p.divide(nTotal))
             else:
-                positions = None
                 velocities = None
             # TODO object envelop (polygon)
             # user type
@@ -1219,8 +1315,6 @@
                 print('The two moving objects have different user types: obj1 {} obj2 {}'.format(userTypeNames[obj1.getUserType()], userTypeNames[obj2.getUserType()]))
 
             newObject = MovingObject(newNum, newTimeInterval, positions, velocities, userType = obj1.getUserType())
-            if hasattr(obj1, 'featureNumbers') and hasattr(obj2, 'featureNumbers'):
-                newObject.featureNumbers = obj1.featureNumbers+obj2.featureNumbers
             if obj1.hasFeatures() and obj2.hasFeatures():
                 newObject.features = obj1.getFeatures()+obj2.getFeatures()
             return newObject