'the length not know'inano.function

Question

我想在DeepLearning教程中對logistic_sgd.py進行一些更改。詳情如下。

原代碼：

index = T.lscalar()  
x = T.matrix('x') 
y = T.ivector('y') 
train_model = theano.function(
     inputs=[index], 
     outputs=classifier.errors(y), 
     givens={ 
      x: test_set_x[index * train_batch_size: (index + 1) * train_batch_size], 
      y: test_set_y[index * train_batch_size: (index + 1) * train_batch_size] 
     } 
    ) 

我的代碼：

index = T.lscalar() 
idx_list = T.lvector() 

x = T.matrix('x') 
y = T.ivector('y') 

train_model = theano.function(
     inputs=[idx_list], 
     outputs=cost, 
     updates=updates, 
     givens={ 
      x: train_set_x[[i for i in idx_list]], 
      y: train_set_y[[i for i in idx_list]] 
     } 
    ) 

我想用train_set_x和train_set_y指數從矢量idx_list，而不是一個原始代碼指數，但我得到以下錯誤：

Traceback (most recent call last): 
    File "Y:/ARBM/code/logistic_sgd_rand.py", line 169, in <module> 
    train_batch_size=5, select_batch_size=10) 
    File "Y:/ARBM/code/logistic_sgd_rand.py", line 92, in sgd_optimization_mnist 
    x: train_set_x[[i for i in idx_list]], 
    File "C:\Anaconda\lib\site-packages\theano\tensor\var.py", line 433, in __iter__ 
    for i in xrange(theano.tensor.basic.get_vector_length(self)): 
    File "C:\Anaconda\lib\site-packages\theano\tensor\basic.py", line 3773, in get_vector_length 
    raise ValueError("length not known") 
ValueError: length not known 

Answer 1

問題是你以不支持的方式將Python與符號Theano代碼混合在一起。

而不是

x: train_set_x[[i for i in idx_list]], 
y: train_set_y[[i for i in idx_list]] 

你需要

x: train_set_x[idx_list], 
y: train_set_y[idx_list] 

以下是一個演示中更詳細一點的改變一個完整的例子：

import numpy 
import theano 
import theano.tensor as T 


def v1(all_x): 
    batch_size = 3 
    index = T.lscalar() 
    x_part = T.vector() 
    f = theano.function(
     inputs=[index], 
     outputs=x_part, 
     givens={ 
      x_part: all_x[index * batch_size: (index + 1) * batch_size] 
     } 
    ) 
    print f(1) 


def v2_broken(all_x): 
    idx_list = T.lvector() 
    x_part = T.vector() 
    f = theano.function(
     inputs=[idx_list], 
     outputs=x_part, 
     givens={ 
      x_part: all_x[[i for i in idx_list]] 
     } 
    ) 
    print f([2, 4, 6, 8]) 


def v2_fixed(all_x): 
    idx_list = T.lvector() 
    x_part = T.vector() 
    f = theano.function(
     inputs=[idx_list], 
     outputs=x_part, 
     givens={ 
      x_part: all_x[idx_list] 
     } 
    ) 
    print f([2, 4, 6, 8]) 


def main(): 
    all_x = theano.shared(-numpy.arange(10, dtype=theano.config.floatX)) 
    v1(all_x) 
    # v2_broken(all_x) # raises ValueError: length not known 
    v2_fixed(all_x) 


main()