add ngrams and phone feature

Author: arushianeja

06-Naive-Bayes/ngrams/2ndhalfnonspam.txt

@@ -0,0 +1,20 @@
+def spamicity_of_given_word(good, bad, word, ngood, nbad):
+    g = 0.0
+    b = 0.0
+    if word in good:
+        g = float(2 * good[word])
+    if word in bad:
+        b = float(bad[word])
+
+
+    if (g+b >= 5):
+        print ("ngood : " + str(ngood) + "      nbad : " + str(nbad))
+        x = b/nbad
+        y = g/ngood
+        print (" b : "+ str(b) + " g : " + str(g))
+        print (" x : " + str(x) + " y : " + str(y))
+        a = min(1, x)/min(1, y + min(1, x))
+        returnVal = max(0.01, min (0.99, a))
+        return returnVal
+    else:
+        return 0.4

06-Naive-Bayes/ngrams/2ndhalfspam.txt

@@ -0,0 +1,84 @@
+#!/usr/bin/env python2.7
+
+
+import sys, os
+import re
+import filtering as filt
+import numpy as np
+import re
+from collections import defaultdict
+
+class PhonePresent:
+	pass
+
+PHONE_NUMBER = PhonePresent()
+
+def create_dictionary(filename):
+	features_freq = defaultdict(float)
+
+	with open(filename, 'r') as fp:
+		for line in fp:
+			words = re.split('\W+', line)
+			sentence = words[1:]
+			features = featurise(sentence)
+			# Start from the second word (ignore the ham/spam marker).
+			for f in features:
+				features_freq[f] += 1
+	return features_freq
+
+
+def featurise(temp_sentence):
+	sentence = []
+	for word in temp_sentence:
+		if re.match("^[0-9]{5}[0-9]*$", word):
+			sentence.append(PHONE_NUMBER)
+		else:
+			sentence.append(word)
+	bigrams = zip(sentence, sentence[1:])
+	trigrams = zip(sentence, sentence[1:], sentence[2:])
+
+	return sentence + bigrams #+ trigrams
+
+def calc_spamprob(message, good, bad):
+	# Split the line in words.
+	features = featurise(re.split('\W+', message))
+	probv = np.array([ filt.spamicity_of_given_word(good,bad,f,4827,747) for f in features])
+	return probv.prod() / (probv.prod()+(1-probv).prod())
+
+def is_spam(message, good, bad):
+	spamprob = calc_spamprob(message, good, bad)
+
+	return spamprob > 0.5
+
+def main(argv):
+	good = create_dictionary('halfnonspam.txt')
+	bad = create_dictionary('halfspam.txt')
+	count_correct = 0.0
+	count_incorrect = 0.0
+
+	with open('2ndhalfspam.txt', 'r') as fp:
+		for line in fp:
+			if is_spam(line[len("spam "):], good, bad):
+				count_correct+=1
+			else:
+				count_incorrect+=1
+
+	with open('2ndhalfnonspam.txt', 'r') as fp:
+		for line in fp:
+			if not is_spam(line[len("ham "):], good, bad):
+				count_correct+=1
+			else:
+				count_incorrect+=1
+
+	accuracy = (count_correct/ (count_correct + count_incorrect))
+	print("Accuracy is: "+ str(accuracy))
+
+	# for word in good:
+	# 	probabilty[word] = filt.populate_third_dict(good, bad, word, 4827, 747)
+	#
+	# for word in bad:
+	# 	probabilty[word] = filt.populate_third_dict(good, bad, word, 4827, 747)
+
+
+if __name__ == '__main__':
+	main(sys.argv[1:])