validate.py 文件源码

def bigram_predict(testSet,PP,PN,positive_probabilities,negative_probabilities,unseen_pos_prob,unseen_neg_prob):
    predicted_class = []
    for review in testSet:
        negative_probab = math.log10(PN)
        positive_probab = math.log10(PP)
        review_words = []
        review_words.append('*')
        review_words.extend(word_tokenize(review))
        review_words.append('$')
        review_bigrams = bigrams(review_words)
        for w in review_bigrams:
            bigram = w
            w = w[0]+" " +w[1]
            if w in negative_probabilities and w in positive_probabilities:
                negative_probab = negative_probab + math.log10(negative_probabilities[w])
                positive_probab = positive_probab + math.log10(positive_probabilities[w])
            else:
                if bigram[0] in negative_probabilities and bigram[0] in positive_probabilities:
                    #if(bigram[0] == '*'):
                    #    negative_probab = negative_probab
                    #    positive_probab = positive_probab
                    #else:
                        #if(negative_probabilities[bigram[0]] < 0 or positive_probabilities[bigram[0]] < 0):
                        #    print("issue with " + bigram[0] + " " + str(negative_probabilities[bigram[0]]) + " " + str(positive_probabilities[bigram[0]]))
                        #if(negative_probabilities[bigram[0]] > 0 and positive_probabilities[bigram[0]] > 0):
                    negative_probab = negative_probab + math.log10(negative_probabilities[bigram[0]])
                    positive_probab = positive_probab + math.log10(positive_probabilities[bigram[0]])
                else:
                    negative_probab = negative_probab + math.log10(unseen_neg_prob)
                    positive_probab = positive_probab + math.log10(unseen_pos_prob)

        if(negative_probab > positive_probab):
            result = '-'
        else:
            result = '+'
        predicted_class.append(result)
    return predicted_class