engine_gist_2.py

cosine_similarity.py

import re, math
from collections import Counter

class CosineSimilarity:
    def __init__(self):
        print("Cosine Similarity initialized")

    @staticmethod
    def cosine_similarity_of(text1, text2):
        #get words first
        first = re.compile(r"[\w']+").findall(text1)
        second = re.compile(r"[\w']+").findall(text2)

        #get dictionary with each word and count.
        vector1 = Counter(first)
        vector2 = Counter(second)

        #convert vectors to set to find common words as intersection
        common = set(vector1.keys()).intersection(set(vector2.keys()))

        dot_product = 0.0

        for i in common:
            #get amount of each common word for both vectors and multiply them then add them together.
            dot_product += vector1[i] * vector2[i]

        squared_sum_vector1 = 0.0
        squared_sum_vector2 = 0.0

        #get squared sum values of word counts from each vector.
        for i in vector1.keys():
            squared_sum_vector1 += vector1[i]**2

        for i in vector2.keys():
            squared_sum_vector2 += vector2[i]**2

        #calculate magnitude with squared sums.
        magnitude = math.sqrt(squared_sum_vector1) * math.sqrt(squared_sum_vector2)

        if not magnitude:
           return 0.0
        else:
           return float(dot_product) / magnitude