added rate monitor decorator

zoetrope/ratemon.py

@@ -0,0 +1,35 @@
+from time import time
+
+
+def ratemon(collection):
+    iterator = enumerate(collection)
+    t_start = t_last = time()
+
+    while True:
+        counter, value = next(iterator)
+
+        t_now = time()
+        delta_start = t_now - t_start
+        delta_last  = t_now - t_last
+        t_last = t_now
+
+        try:
+            rate_average = (counter + 1) / delta_start
+        except ZeroDivisionError:
+            rate_average = 0
+
+        try:
+            rate_current = 1 / delta_last
+        except ZeroDivisionError:
+            rate_current = 0
+
+        yield rate_average, rate_current, value
+
+
+
+#TODO:
+#- define averaging window?
+#- round results?
+
+
+