Tensorflow : how to insert custom input to existing graph? - graph

Question

I have downloaded a tensorflow GraphDef that implements a VGG16 ConvNet, which I use doing this :
Pl['images'] = tf.placeholder(tf.float32,
[None, 448, 448, 3],
name="images") #batch x width x height x channels
with open("tensorflow-vgg16/vgg16.tfmodel", mode='rb') as f:
fileContent = f.read()
graph_def = tf.GraphDef()
graph_def.ParseFromString(fileContent)
tf.import_graph_def(graph_def, input_map={"images": Pl['images']})
Besides, I have image features that are homogeneous to the output of the "import/pool5/".
How can I tell my graph that don't want to use his input "images", but the tensor "import/pool5/" as input ?
Thank's !
EDIT
OK I realize I haven't been very clear. Here is the situation:
I am trying to use this implementation of ROI pooling, using a pre-trained VGG16, which I have in the GraphDef format. So here is what I do:
First of all, I load the model:
tf.reset_default_graph()
with open("tensorflow-vgg16/vgg16.tfmodel",
mode='rb') as f:
fileContent = f.read()
graph_def = tf.GraphDef()
graph_def.ParseFromString(fileContent)
graph = tf.get_default_graph()
Then, I create my placeholders
images = tf.placeholder(tf.float32,
[None, 448, 448, 3],
name="images") #batch x width x height x channels
boxes = tf.placeholder(tf.float32,
[None,5], # 5 = [batch_id,x1,y1,x2,y2]
name = "boxes")
And I define the output of the first part of the graph to be conv5_3/Relu
tf.import_graph_def(graph_def,
input_map={'images':images})
out_tensor = graph.get_tensor_by_name("import/conv5_3/Relu:0")
So, out_tensor is of shape [None,14,14,512]
Then, I do the ROI pooling:
[out_pool,argmax] = module.roi_pool(out_tensor,
boxes,
7,7,1.0/1)
With out_pool.shape = N_Boxes_in_batch x 7 x 7 x 512, which is homogeneous to pool5. I would then like to feed out_pool as an input to the op that comes just after pool5, so it would look like
tf.import_graph_def(graph.as_graph_def(),
input_map={'import/pool5':out_pool})
But it doesn't work, I have this error:
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-89-527398d7344b> in <module>()
5
6 tf.import_graph_def(graph.as_graph_def(),
----> 7 input_map={'import/pool5':out_pool})
8
9 final_out = graph.get_tensor_by_name("import/Relu_1:0")
/usr/local/lib/python3.4/dist-packages/tensorflow/python/framework/importer.py in import_graph_def(graph_def, input_map, return_elements, name, op_dict)
333 # NOTE(mrry): If the graph contains a cycle, the full shape information
334 # may not be available for this op's inputs.
--> 335 ops.set_shapes_for_outputs(op)
336
337 # Apply device functions for this op.
/usr/local/lib/python3.4/dist-packages/tensorflow/python/framework/ops.py in set_shapes_for_outputs(op)
1610 raise RuntimeError("No shape function registered for standard op: %s"
1611 % op.type)
-> 1612 shapes = shape_func(op)
1613 if len(op.outputs) != len(shapes):
1614 raise RuntimeError(
/home/hbenyounes/vqa/roi_pooling_op_grad.py in _roi_pool_shape(op)
13 channels = dims_data[3]
14 print(op.inputs[1].name, op.inputs[1].get_shape())
---> 15 dims_rois = op.inputs[1].get_shape().as_list()
16 num_rois = dims_rois[0]
17
/usr/local/lib/python3.4/dist-packages/tensorflow/python/framework/tensor_shape.py in as_list(self)
745 A list of integers or None for each dimension.
746 """
--> 747 return [dim.value for dim in self._dims]
748
749 def as_proto(self):
TypeError: 'NoneType' object is not iterable
Any clue ?

Answer 1

It is usually very convenient to use tf.train.export_meta_graph to store the whole MetaGraph. Then, upon restoring you can use tf.train.import_meta_graph, because it turns out that it passes all additional arguments to the underlying import_scoped_meta_graph which has the input_map argument and utilizes it when it gets to it's own invocation of import_graph_def.
It is not documented, and took me waaaay toooo much time to find it, but it works!

Answer 2

What I would do is something along those lines:
-First retrieve the names of the tensors representing the weights and biases of the 3 fully connected layers coming after pool5 in VGG16.
To do that I would inspect [n.name for n in graph.as_graph_def().node].
(They probably look something like import/locali/weight:0, import/locali/bias:0, etc.)
-Put them in a python list:
weights_names=["import/local1/weight:0" ,"import/local2/weight:0" ,"import/local3/weight:0"]
biases_names=["import/local1/bias:0" ,"import/local2/bias:0" ,"import/local3/bias:0"]
-Define a function that look something like:
def pool5_tofcX(input_tensor, layer_number=3):
flatten=tf.reshape(input_tensor,(-1,7*7*512))
tmp=flatten
for i in xrange(layer_number):
tmp=tf.matmul(tmp, graph.get_tensor_by_name(weights_name[i]))
tmp=tf.nn.bias_add(tmp, graph.get_tensor_by_name(biases_name[i]))
tmp=tf.nn.relu(tmp)
return tmp
Then define the tensor using the function:
wanted_output=pool5_tofcX(out_pool)
Then you are done !

Answer 3

Jonan Georgiev provided an excellent answer here. The same approach was also described with little fanfare at the end of this git issue: https://github.com/tensorflow/tensorflow/issues/3389
Below is a copy/paste runnable example of using this approach to switch out a placeholder for a tf.data.Dataset get_next tensor.
import tensorflow as tf
my_placeholder = tf.placeholder(dtype=tf.float32, shape=1, name='my_placeholder')
my_op = tf.square(my_placeholder, name='my_op')
# Save the graph to memory
graph_def = tf.get_default_graph().as_graph_def()
print('----- my_op before any remapping -----')
print([n for n in graph_def.node if n.name == 'my_op'])
tf.reset_default_graph()
ds = tf.data.Dataset.from_tensors(1.0)
next_tensor = tf.data.make_one_shot_iterator(ds).get_next(name='my_next_tensor')
# Restore the graph with a custom input mapping
tf.graph_util.import_graph_def(graph_def, input_map={'my_placeholder': next_tensor}, name='')
print('----- my_op after remapping -----')
print([n for n in tf.get_default_graph().as_graph_def().node if n.name == 'my_op'])
Output, where we can clearly see that the input to the square operation has changed.
----- my_op before any remapping -----
[name: "my_op"
op: "Square"
input: "my_placeholder"
attr {
key: "T"
value {
type: DT_FLOAT
}
}
]
----- my_op after remapping -----
[name: "my_op"
op: "Square"
input: "my_next_tensor"
attr {
key: "T"
value {
type: DT_FLOAT
}
}
]