cosine

cosine.py

def cosine(dot_product, rating_norm_squared, rating2_norm_squared):
    '''
    The cosine between two vectors A, B
       dotProduct(A, B) / (norm(A) * norm(B))
    '''
    numerator = dot_product
    denominator = rating_norm_squared * rating2_norm_squared

    return (numerator / (float(denominator))) if denominator else 0.0