tensorflow tensor 索引

问题：

self.q_eval4next： （100,2）

ix=【0,1,0,1---0，1】（100,1）

我想取q_eval4next[:,idx]

         #use_doubleQ  切片用！！！！
         self.range_index = tf.placeholder(tf.int32,[None,],name='range_index')

         if self.use_doubleQ:

             f = tf.map_fn(lambda x: x, self.range_index) # or perhaps something more useful than identity
             ix = tf.to_int32(tf.expand_dims(tf.argmax(self.q_eval4next,axis=1),-1))
             tmp=tf.to_int32(tf.expand_dims(f,-1))
             index_a = tf.concat([tmp,ix,],axis=1)
             maxq =  tf.gather_nd(self.q_next,index_a)

https://www.programcreek.com/python/example/90420/tensorflow.map_fn

https://*.com/questions/34987509/tensorflow-max-of-a-tensor-along-an-axis

https://zhuanlan.zhihu.com/p/39295071

https://zhuanlan.zhihu.com/p/45673869