models.py 文件源码

def prod_all_but_j(vector):
    """ returns a vector where the jth term is the product of all the entries except the jth one """
    zeros = np.where(vector==0)[0]
    if len(zeros) > 1:
        return np.zeros(len(vector))
    if len(zeros) == 1:
        result = np.zeros(len(vector))
        j = zeros[0]
        result[j] = np.prod(vector[np.arange(len(vector)) != j])
        return result

    joint = np.prod(vector)
    return np.true_divide(joint,vector)