--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/trafficintelligence/sensors.py	Fri Jun 15 11:19:10 2018 -0400
@@ -0,0 +1,65 @@
+#! /usr/bin/env python
+'''Libraries for detecting, counting, etc., road users'''
+
+from numpy import mean, isnan
+
+from trafficintelligence import moving
+
+# TODO graphical user interface for creation
+
+class Sensor:
+    def detect(self, o):
+        print("Detect method not implemented")
+        return False
+    
+    def detectInstants(self, o):
+        print("DetectInstants method not implemented")
+        return []
+
+class BoxSensor(Sensor):
+    def __init__(self, polygon, minNPointsInBox = 1):
+        self.polygon = polygon # check 2xN?
+        self.minNPointsInBox = minNPointsInBox
+    
+    def detectInstants(self, obj):
+        indices = obj.getPositions().getInstantsInPolygon(self.polygon)
+        firstInstant = obj.getFirstInstant()
+        return [i+firstInstant for i in indices]
+
+    def detect(self, obj):
+        instants = self.detectInstants(obj)
+        return len(instants) >= self.minNPointsInBox
+
+def detectAnd(sensors, obj):
+    'Returns True if all sensors detect the object'
+    result = True
+    for s in sensors:
+        result = result and s.detect(obj)
+        if not result:
+            return result
+    return result
+
+def detectOr(sensors, obj):
+    'Returns True if any sensor detects the object'
+    result = False
+    for s in sensors:
+        result = result or s.detect(obj)
+        if result:
+            return result
+    return result
+
+def detectAndOrder(sensors, obj):
+    'Returns True if all sensors are detected and in their order'
+    detectionInstants = []
+    for s in sensors:
+        instants = s.detectInstants(obj)
+        if len(instants) == 0:
+            return False
+        else:
+            detectionInstants.append(mean(instants))
+    result = True
+    for i in range(len(sensors)-1):
+        result = result and (detectionInstants[i] <= detectionInstants[i+1])
+        if not result:
+            return result
+    return result