Merge pull request #10 from Qukaiyi/add-type-check-for-ClassifierFeat…

…ure-1

Update __init__ method of meta.py

nel/features/meta.py

@@ -10,8 +10,11 @@
 
 class ClassifierFeature(Feature):
     """ Computes a feature score based on the output of a classifier over a set of features. """
-    def __init__(self, classifier):
-        self.classifier = classifier
+    def __init__(self, classifier=None, classifier_model_tag=None):
+        if (classifier_model_tag is None) == (classifier is None):
+            raise Exception('You must provide a classifier_model_tag or classifier instance, but not both.')
+        self.classifier = classifier or Classifier.load(classifier_model_tag) 
+
 
     def compute_doc_state(self, doc):
         doc = self.classifier.mapper(doc) 
@@ -41,3 +44,4 @@ def id(self):
 
     def predict(self, fv):
         return self.classifier.model.predict_proba(fv)[0][1]
+