如何正确地将特定张量输入到keras模型

Question

为了允许将Keras模型用作标准tensorflow操作的一部分，我使用输入的特定占位符创建一个模型。

但是，当尝试执行model.predict时，出现错误：

InvalidArgumentError (see above for traceback): You must feed a value for placeholder tensor 'Placeholder' with dtype float and shape [100,84,84,4]
 [[Node: Placeholder = Placeholder[dtype=DT_FLOAT, shape=[100,84,84,4], _device="/job:localhost/replica:0/task:0/cpu:0"]()]]

我的代码如下：

from keras.layers import Convolution2D, Dense, Input
from keras.models import Model
from keras.optimizers import Nadam
from keras.losses import mean_absolute_error
from keras.activations import relu
import tensorflow as tf
import numpy as np
import gym

state_size = [100, 84, 84, 4]

input_tensor = tf.placeholder(dtype=tf.float32, shape=state_size)

inputL = Input(tensor=input_tensor)
h1 = Convolution2D(filters=32, kernel_size=(5,5), strides=(4,4), activation=relu) (inputL)
h2 = Convolution2D(filters=64, kernel_size=(3,3), strides=(2,2), activation=relu) (h1)
h3 = Convolution2D(filters=64, kernel_size=(3,3), activation=relu) (h2)
h4 = Dense(512, activation=relu) (h3)
out = Dense(18) (h4)

model = Model(inputL, out)

opt = Nadam()


disc_rate=0.99

sess = tf.Session()
dummy_input = np.ones(shape=state_size)

model.compile(opt, mean_absolute_error)

writer = tf.summary.FileWriter('./my_graph', sess.graph)
writer.close()

print(out)

print(model.predict({input_tensor: dummy_input}))

我也尝试直接输入输入（没有字典，只有值）-同样的例外。但是，我可以使模型像这样工作：

print(sess.run( model.output, {input_tensor: dummy_input }))

有没有办法让我仍然使用普通的Keras .p​​redict方法？

Answer 1

以下工作（我们需要初始化全局变量）：

sess.run(tf.global_variables_initializer()) # initialize 
print(sess.run([model.output], feed_dict={input_tensor: dummy_input}))