书上的一个实例，不知道为什么报错。请各位大神帮忙解答一下。
程序如下：
from tensorflow.examples.tutorials.mnist import input_data
mnist=input_data.read_data_sets("MNIST_data/",one_hot=True)
print(mnist.train.images.shape,mnist.train.labels.shape)
print(mnist.test.images.shape,mnist.test.labels.shape)
print(mnist.validation.images.shape,mnist.validation.labels.shape)
import tensorflow as tf
sess=tf.InteractiveSession()
x=tf.placeholder(tf.float32,[None,784])
W=tf.Variable(tf.zeros([784,10]))
b=tf.Variable(tf.zeros([10]))
y=tf.nn.softmax(tf.matmul(x,W)+b)
y_=tf.placeholder(tf.float32,[None,10])
cross_entropy=tf.reduce_mean(-tf.reduce_sum(y_* tf.log(y),reduction_indices=[1]))
train_step=tf.train.GradientDescentOptimizer(0.5).minimize(cross_entropy)
tf.global_variables_initializer().run()
for i in range(1000):
batch_xs,batch_ys=mnist.train.next_batch(100)
train_step.run({x:batch_xs,y_:batch_ys})
correct_prediction=tf.equal(tf.argmax(y,1),tf.argmax(y_,1))
accuracy=tf.reduce_mean(tf.cast(correct_prediction,tf.float32))
print(accuracy.eval({x:mnist.test.images,y:mnist.test.labels}))
报错如下：
runfile('D:/project/Spyder/MNIST_data.py', wdir='D:/project/Spyder')
Extracting MNIST_data/train-images-idx3-ubyte.gz
Extracting MNIST_data/train-labels-idx1-ubyte.gz
Extracting MNIST_data/t10k-images-idx3-ubyte.gz
Extracting MNIST_data/t10k-labels-idx1-ubyte.gz
(55000, 784) (55000, 10)
(10000, 784) (10000, 10)
(5000, 784) (5000, 10)
D:\soft\Anaconda3\lib\site-packages\tensorflow\python\client\session.py:1645: UserWarning: An interactive session is already active. This can cause out-of-memory errors in some cases. You must explicitly call InteractiveSession.close() to release resources held by the other session(s).
warnings.warn('An interactive session is already active. This can '
Traceback (most recent call last):
File "", line 1, in
runfile('D:/project/Spyder/MNIST_data.py', wdir='D:/project/Spyder')
File "D:\soft\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 705, in runfile
execfile(filename, namespace)
File "D:\soft\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 102, in execfile
exec(compile(f.read(), filename, 'exec'), namespace)
File "D:/project/Spyder/MNIST_data.py", line 29, in
print(accuracy.eval({x:mnist.test.images,y:mnist.test.labels}))
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\framework\ops.py", line 680, in eval
return _eval_using_default_session(self, feed_dict, self.graph, session)
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\framework\ops.py", line 4951, in _eval_using_default_session
return session.run(tensors, feed_dict)
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\client\session.py", line 877, in run
run_metadata_ptr)
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\client\session.py", line 1100, in _run
feed_dict_tensor, options, run_metadata)
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\client\session.py", line 1272, in _do_run
run_metadata)
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\client\session.py", line 1291, in _do_call
raise type(e)(node_def, op, message)
InvalidArgumentError: You must feed a value for placeholder tensor 'Placeholder_3' with dtype float and shape [?,10]
[[Node: Placeholder_3 = Placeholderdtype=DT_FLOAT, shape=[?,10], _device="/job:localhost/replica:0/task:0/device:GPU:0"]]
[[Node: Mean_3/_29 = _Recvclient_terminated=false, recv_device="/job:localhost/replica:0/task:0/device:CPU:0", send_device="/job:localhost/replica:0/task:0/device:GPU:0", send_device_incarnation=1, tensor_name="edge_18_Mean_3", tensor_type=DT_FLOAT, _device="/job:localhost/replica:0/task:0/device:CPU:0"]]
Caused by op 'Placeholder_3', defined at:
File "D:\soft\Anaconda3\lib\site-packages\spyder\utils\ipython\start_kernel.py", line 268, in
main()
File "D:\soft\Anaconda3\lib\site-packages\spyder\utils\ipython\start_kernel.py", line 264, in main
kernel.start()
File "D:\soft\Anaconda3\lib\site-packages\ipykernel\kernelapp.py", line 478, in start
self.io_loop.start()
File "D:\soft\Anaconda3\lib\site-packages\zmq\eventloop\ioloop.py", line 177, in start
super(ZMQIOLoop, self).start()
File "D:\soft\Anaconda3\lib\site-packages\tornado\ioloop.py", line 888, in start
handler_func(fd_obj, events)
File "D:\soft\Anaconda3\lib\site-packages\tornado\stack_context.py", line 277, in null_wrapper
return fn(*args, **kwargs)
File "D:\soft\Anaconda3\lib\site-packages\zmq\eventloop\zmqstream.py", line 440, in handle_events
self._handle_recv()
File "D:\soft\Anaconda3\lib\site-packages\zmq\eventloop\zmqstream.py", line 472, in _handle_recv
self._run_callback(callback, msg)
File "D:\soft\Anaconda3\lib\site-packages\zmq\eventloop\zmqstream.py", line 414, in _run_callback
callback(*args, **kwargs)
File "D:\soft\Anaconda3\lib\site-packages\tornado\stack_context.py", line 277, in null_wrapper
return fn(*args, **kwargs)
File "D:\soft\Anaconda3\lib\site-packages\ipykernel\kernelbase.py", line 283, in dispatcher
return self.dispatch_shell(stream, msg)
File "D:\soft\Anaconda3\lib\site-packages\ipykernel\kernelbase.py", line 233, in dispatch_shell
handler(stream, idents, msg)
File "D:\soft\Anaconda3\lib\site-packages\ipykernel\kernelbase.py", line 399, in execute_request
user_expressions, allow_stdin)
File "D:\soft\Anaconda3\lib\site-packages\ipykernel\ipkernel.py", line 208, in do_execute
res = shell.run_cell(code, store_history=store_history, silent=silent)
File "D:\soft\Anaconda3\lib\site-packages\ipykernel\zmqshell.py", line 537, in run_cell
return super(ZMQInteractiveShell, self).run_cell(*args, **kwargs)
File "D:\soft\Anaconda3\lib\site-packages\IPython\core\interactiveshell.py", line 2728, in run_cell
interactivity=interactivity, compiler=compiler, result=result)
File "D:\soft\Anaconda3\lib\site-packages\IPython\core\interactiveshell.py", line 2856, in run_ast_nodes
if self.run_code(code, result):
File "D:\soft\Anaconda3\lib\site-packages\IPython\core\interactiveshell.py", line 2910, in run_code
exec(code_obj, self.user_global_ns, self.user_ns)
File "", line 1, in
runfile('D:/project/Spyder/MNIST_data.py', wdir='D:/project/Spyder')
File "D:\soft\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 705, in runfile
execfile(filename, namespace)
File "D:\soft\Anaconda3\lib\site-packages\spyder\utils\site\sitecustomize.py", line 102, in execfile
exec(compile(f.read(), filename, 'exec'), namespace)
File "D:/project/Spyder/MNIST_data.py", line 20, in
y=tf.placeholder(tf.float32,[None,10])
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\ops\array_ops.py", line 1735, in placeholder
return gen_array_ops.placeholder(dtype=dtype, shape=shape, name=name)
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\ops\gen_array_ops.py", line 5928, in placeholder
"Placeholder", dtype=dtype, shape=shape, name=name)
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\framework\op_def_library.py", line 787, in apply_op_helper
op_def=op_def)
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\util\deprecation.py", line 454, in new_func
return func(*args, **kwargs)
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\framework\ops.py", line 3155, in create_op
op_def=op_def)
File "D:\soft\Anaconda3\lib\site-packages\tensorflow\python\framework\ops.py", line 1717, in __init_
self._traceback = tf_stack.extract_stack()
InvalidArgumentError (see above for traceback): You must feed a value for placeholder tensor 'Placeholder_3' with dtype float and shape [?,10]
[[Node: Placeholder_3 = Placeholderdtype=DT_FLOAT, shape=[?,10], _device="/job:localhost/replica:0/task:0/device:GPU:0"]]
[[Node: Mean_3/_29 = _Recvclient_terminated=false, recv_device="/job:localhost/replica:0/task:0/device:CPU:0", send_device="/job:localhost/replica:0/task:0/device:GPU:0", send_device_incarnation=1, tensor_name="edge_18_Mean_3", tensor_type=DT_FLOAT, _device="/job:localhost/replica:0/task:0/device:CPU:0"]]
