listwise.py 文件源码

def listnet(x, t):
    """
    The Top-1 approximated ListNet loss as in Cao et al (2006), Learning to
    Rank: From Pairwise Approach to Listwise Approach

    :param x: The activation of the previous layer 
    :param t: The target labels
    :return: The loss
    """

    # ListNet top-1 reduces to a softmax and simple cross entropy
    st = F.softmax(t, axis=0)
    sx = F.softmax(x, axis=0)
    return -F.mean(st * F.log(sx))