diff --git a/zipline/algorithm.py b/zipline/algorithm.py
index 7622c665..6e61ccdd 100644
--- a/zipline/algorithm.py
+++ b/zipline/algorithm.py
@@ -43,6 +43,10 @@ from zipline import MESSAGES
 
 DEFAULT_CAPITAL_BASE = float("1.0e5")
 
+ANNUALIZER = {'daily': 250,
+              'hourly': 250 * 6,
+              'minutely': 250 * 6 * 60}
+
 
 class TradingAlgorithm(object):
     """Base class for trading algorithms. Inherit and overload
@@ -110,17 +114,7 @@ class TradingAlgorithm(object):
         # this is happening after initialize because granularity
         # could be set in there.
         if self.annualizer is None:
-            if self.granularity == 'daily':
-                self.annualizer = 250
-            elif self.granularity == 'hourly':
-                # trading days * hours
-                self.annualizer = 250 * 6
-            elif self.granularity == 'minutely':
-                # trading days * hours * minutes
-                self.annualizer = 250 * 6 * 60
-            else:
-                raise NotImplementedError('{g} is not implemented.\
-                                          '.format(g=self.granularity))
+            self.annualizer = ANNUALIZER[self.granularity]
 
     def _create_generator(self, environment):
         """
@@ -323,3 +317,7 @@ class TradingAlgorithm(object):
     def set_transforms(self, transforms):
         assert isinstance(transforms, list)
         self.transforms = transforms
+
+    def set_granuliarity(self, granularity):
+        assert granularity in ('daily', 'minute')
+        self.granularity = granularity