mmd.py 文件源码

def _mmd2(K_XX, K_XY, K_YY, const_diagonal=False, biased=False):
    m = tf.cast(K_XX.get_shape()[0], tf.float32)
    n = tf.cast(K_YY.get_shape()[0], tf.float32)
   # m=50
    #n=50
    if biased:
        mmd2 = (tf.reduce_sum(K_XX) / (m * m)
              + tf.reduce_sum(K_YY) / (n * n)
              - 2 * tf.reduce_sum(K_XY) / (m * n))
    else:
        if const_diagonal is not False:
            trace_X = m * const_diagonal
            trace_Y = n * const_diagonal
        else:
            trace_X = tf.trace(K_XX)
            trace_Y = tf.trace(K_YY)

        mmd2 = ((tf.reduce_sum(K_XX) - trace_X) / (m * (m - 1))
              + (tf.reduce_sum(K_YY) - trace_Y) / (n * (n - 1))
              - 2 * tf.reduce_sum(K_XY) / (m * n))

    return mmd2