new tfidf script

tfidf.py

@@ -0,0 +1,13 @@
+import pymongo
+from pymongo import Connection
+MONGODB_PORT = 27017
+import nltk
+from nltk.corpus import brown
+from nltk.text import TextCollection
+mongodb=Connection("localhost", MONGODB_PORT)['cablegate']
+browntext = TextCollection(brown.words(categories=['news','government']))
+count=0
+for ng in mongodb.ngrams.find(timeout=False):
+	mongodb.ngrams.update({"_id":ng["_id"]},{"$set":{"tfidf": browntext.tf_idf(ng['label'],brown.words(categories=['news','government'])) }})
+	count+=1
+	print "updated tfidf for %d topics"%count