ValueError异常的tensorflow while_loop形状不变

Question

import tensorflow as tf 

cluster_size = tf.constant(6) # size of the cluster 
m = tf.constant(6) # number of contigs (column size) 
n = tf.constant(3) # number of points in a single contigs (column size) 
contigs_index = tf.reshape(tf.range(0, m, 1, dtype=tf.int32), [1, -1]) 
contigs = tf.constant(
    [[1.1, 2.2, 3.3], [6.6, 5.5, 4.4], [7.7, 8.8, 9.9], [11.1, 22.2, 33.3], 
    [66.6, 55.5, 44.4], [77.7, 88.8, 99.9]]) 

# pad zeo to the right till fixed length 
def rpad_with_zero(points): 
    points = tf.slice(tf.pad(points, tf.reshape(tf.concat(
    [tf.zeros([1, 2], tf.int32), tf.add(
     tf.zeros([1, 2], tf.int32), 
     tf.subtract(cluster_size, tf.size(points)))], 0), [2, -1]), "CONSTANT"), 
        (0, tf.subtract(cluster_size, tf.size(points))), 
        (1, cluster_size)) 
    return points 

#calculate pearson correlation coefficient r value 
def calculate_pcc(row, contigs): 
    r = tf.divide(tf.subtract(
     tf.multiply(tf.to_float(n), tf.reduce_sum(tf.multiply(row, contigs), 1)), 
     tf.multiply(tf.reduce_sum(row, 1), tf.reduce_sum(contigs, 1))), 
       tf.multiply(
     tf.sqrt(tf.subtract(
     tf.multiply(tf.to_float(n), tf.reduce_sum(tf.square(row), 1)), 
     tf.square(tf.reduce_sum(row, 1)))), 
     tf.sqrt(tf.subtract(tf.multiply(
     tf.to_float(n), tf.reduce_sum(tf.square(contigs), 1)), 
     tf.square(tf.reduce_sum(contigs, 1))) 
    ))) 
    return r 

#slice first row from contigs 
row = tf.slice(contigs, (0, 0), (1, 3)) 
#calculate pcc 
r = calculate_pcc(row, contigs) 
#cluster member index whose r value is greater than 0.90, then casting to 
# int32, 
members0_index = tf.cast(tf.reshape(tf.where(tf.greater(r, 0.90)), [1, -1]), 
         tf.int32) 
#members = index <intersection> members, padding the members index with 
# zeros at right, to keep the fixed cluster length 
members0_index = rpad_with_zero(
    tf.reshape(tf.sets.set_intersection(contigs_index, members0_index).values, 
      [1, -1])) 
#update index with the rest element index from contigs, and padding 
contigs_index = rpad_with_zero(
    tf.reshape(tf.sets.set_difference(contigs_index, members0_index).values, 
      [1, -1])) 

#def condition(contigs, contigs_index, members0_index): 
def condition(contigs_index, members0_index): 
    return tf.greater(tf.count_nonzero(contigs_index), 
        0) # iterate until there is a contig 

#def body(contigs, contigs_index, members0_index): 
def body(contigs_index, members0_index): 
    i = tf.reshape(tf.slice(contigs_index, [0, 0], [1, 1]), 
       []) #the first element in the contigs_index 
    row = tf.slice(contigs, (i, 0), 
       (1, 3)) #slice the ith contig from contigs 
    r = calculate_pcc(row, contigs) 
    members_index = tf.cast(tf.reshape(tf.where(tf.greater(r, 0.90)), [1, -1]), 
          tf.int32) 
    members_index = rpad_with_zero(rpad_with_zero(
    tf.reshape(tf.sets.set_intersection(contigs_index, members_index).values, 
       [1, -1]))) 
    members0_index = tf.concat([members0_index, members_index], 0) 
    contigs_index = rpad_with_zero(
    tf.reshape(tf.sets.set_difference(contigs_index, members_index).values, 
       [1, -1])) 
    #return [contigs, contigs_index, members0_index] 
    return [contigs_index, members0_index] 

sess = tf.Session() 
sess.run(tf.while_loop(condition, body, 
    #loop_vars=[contigs, contigs_index, members0_index], 
    loop_vars=[contigs_index, members0_index], 
    #shape_invariants=[contigs.get_shape(), contigs_index.get_shape(), 
    # tf.TensorShape([None, 6])])) 
    shape_invariants=[contigs_index.get_shape(), tf.TensorShape([None, 6])])) 

的错误是：

ValueError: The shape for while_12/Merge:0 is not an invariant for the loop. It enters the loop with shape (1, 6), but has shape (?, ?) after one iteration. Provide shape invariants using either the shape_invariants argument of tf.while_loop or set_shape() on the loop variables.

看来变量

contigs_index

负责，但我真的不知道为什么！我展开循环执行每个语句，但无法找到任何形状不匹配！

Answer 1

您必须在图中使用tf.while_loop，而不是会话。即，见教程https://sebastianraschka.com/pdf/books/dlb/appendix_g_tensorflow.pdf或官方tensorflow文档在https://www.tensorflow.org/api_guides/python/control_flow_ops控制流一节中关于如何使用条件运算符的更多信息，tf.while_loop小号等

Answer 2

shape_invariants=[contigs_index.get_shape(), tf.TensorShape([None, 6])]))应该成为shape_invariants=[tf.TensorShape([None, None]), tf.TensorShape([None, 6])]))，允许contigs_index变量的形状发生变化（在rpad_with_zero调用中）。