linear interpolate schedule

tensorpack/callbacks/param.py

@@ -161,20 +161,38 @@ class ScheduledHyperParamSetter(HyperParamSetter):
     """
     Set hyperparameters by a predefined schedule.
     """
-    def __init__(self, param, schedule):
+    def __init__(self, param, schedule, interp=None):
         """
         :param schedule: [(epoch1, val1), (epoch2, val2), (epoch3, val3), ...]
             The value is fixed to val1 in epoch [epoch1, epoch2), and so on.
+        :param interp: None: no interpolation. 'linear': linear interpolation
         """
         schedule = [(int(a), float(b)) for a, b in schedule]
         self.schedule = sorted(schedule, key=operator.itemgetter(0))
+        if interp is not None:
+            assert interp == 'linear'
+        self.interp = interp
         super(ScheduledHyperParamSetter, self).__init__(param)
 
     def _get_value_to_set(self):
-        for e, v in self.schedule:
-            if e == self.epoch_num:
-                return v
-        return None
+        if self.interp is None:
+            for e, v in self.schedule:
+                if e == self.epoch_num:
+                    return v
+            return None
+        else:
+            laste, lastv = None, None
+            for e, v in self.schedule:
+                if e == self.epoch_num:
+                    return v
+                if e > self.epoch_num:
+                    break
+                laste, lastv = e, v
+            if laste is None or laste == e:
+                # hasn't reached the first scheduled point, or reached the end of all scheduled points
+                return None
+            v = (self.epoch_num - laste) * 1. / (e - laste) * (v - lastv) + lastv
+            return v
 
 class StatMonitorParamSetter(HyperParamSetter):
     """