Source code for similarityPy.measure.numerical_data.cosine_distance

# coding=utf-8
"""
Created on 18 January 2014
@author: Cenk Bircanoglu
"""
import operator

from similarityPy.measure.similarity_measure import SimilarityMeasure
from similarityPy.measure.similarity_measure_type import SimilarityMeasureType
from similarityPy.algorithms.norm import Norm


[docs]class CosineDistance(SimilarityMeasure):
    similarity_measure_type = SimilarityMeasureType.DISTANCE_RATIO_ABBR

    def _algorithm(self):
        if len(self._data) == 2:
            point_a = self._data[0]
            point_b = self._data[1]

            if len(point_a) == len(point_b):
                try:
                    dividend = sum(map(operator.mul, point_b, point_a))
                    divider = Norm.calculate(point_b) * Norm.calculate(point_a)
                    self._result = 1 - (dividend / divider)
                except:
                    raise
            else:
                raise ArithmeticError("You cant calculate Cosine distance of array has different sizes.")
        else:
            raise ArithmeticError("You must enter two array to find Cosine distance.")