python – 在Tensorflow中打印张量的值

https://github.com/roshanDD/YAD2K/blob/master/yad2k/models/keras_yolo.py#L253

我只想打印张量的值,称为true_areas.我运行了我的代码：

sess = tf.InteractiveSession()
true_areas = true_wh[...,0] * true_wh[...,1]
tf.Print(true_areas,[true_areas],message = "This is True Areas: ")
b = tf.add(true_areas,true_areas).eval()

但它给了我错误：

Caused by op 'input_2',defined at:
  File "learning.py",line 358,in <module>
    _main(args)
  File "learning.py",line 66,in _main
    model_body,model = create_model(anchors,class_names)
  File "learning.py",line 185,in create_model
    boxes_input = Input(shape=(None,5))
  File "/home/ubuntu/anaconda2/envs/py35/lib/python3.5/site-packages/keras/engine/topology.py",line 1388,in Input
    input_tensor=tensor)
  File "/home/ubuntu/anaconda2/envs/py35/lib/python3.5/site-packages/keras/engine/topology.py",line 1299,in __init__
    name=self.name)
  File "/home/ubuntu/anaconda2/envs/py35/lib/python3.5/site-packages/keras/backend/tensorflow_backend.py",line 349,in placeholder
    x = tf.placeholder(dtype,shape=shape,name=name)
  File "/home/ubuntu/anaconda2/envs/py35/lib/python3.5/site-packages/tensorflow/python/ops/array_ops.py",line 1507,in placeholder
    name=name)
  File "/home/ubuntu/anaconda2/envs/py35/lib/python3.5/site-packages/tensorflow/python/ops/gen_array_ops.py",line 1997,in _placeholder
    name=name)
  File "/home/ubuntu/anaconda2/envs/py35/lib/python3.5/site-packages/tensorflow/python/framework/op_def_library.py",line 768,in apply_op
    op_def=op_def)
  File "/home/ubuntu/anaconda2/envs/py35/lib/python3.5/site-packages/tensorflow/python/framework/ops.py",line 2336,in create_op
    original_op=self._default_original_op,op_def=op_def)
  File "/home/ubuntu/anaconda2/envs/py35/lib/python3.5/site-packages/tensorflow/python/framework/ops.py",line 1228,in __init__
    self._traceback = _extract_stack()

InvalidArgumentError (see above for traceback): You must feed a value for placeholder tensor 'input_2' with dtype float
     [[Node: input_2 = Placeholder[dtype=DT_FLOAT,shape=[],_device="/job:localhost/replica:0/task:0/cpu:0"]()]]

它正在谈论的占位符是什么？