Convert arbitrary rank dense tensor to sparse tensor

tf_dense_to_sparse.py

  def dense_to_sparse(t): 
    num_elements = tf.reduce_prod(tf.shape(t)) 
    def _index_dim(dim): 
      return tf.reshape( 
        tf.tile( 
          tf.expand_dims(tf.range(0, dim), -1), 
          multiples=[1, num_elements/dim] 
        ), 
        [-1] 
      ) 
   
    index_dims = tf.map_fn(_index_dim, tf.shape(t)) 
    return tf.SparseTensor( 
      indices=tf.transpose(index_dims), 
      values=tf.reshape(t, [-1]) 
      dense_shape=tf.shape(t) 
    )