余弦相似度测量

//cos 相似性度量
float cos_distance(const std::vector<float>& vecfeature1, vector<float>& vecfeature2)
{
    float cos_dis=0;
    float dotmal=0, norm1=0, norm2=0;
    for (int i = 0; i < vecfeature1.size(); i++)
    {
        dotmal += vecfeature1[i] * vecfeature2[i];
        norm1 += vecfeature1[i] * vecfeature1[i];
        norm2 += vecfeature2[i] * vecfeature2[i];

    }
    norm1 = sqrt(norm1);
    norm2 = sqrt(norm2);
    cos_dis = dotmal / (norm1*norm2);
    return cos_dis;
}


返回越接近1 差异越小