Prediction from tensorflow model fails - python-3.x

Question

I am extremely new to tensorflow and trying to learn how to save and load a previously trained model. I created a simple model using Estimator and trained it.
classifier = tf.estimator.Estimator(model_fn=bag_of_words_model)
# Train
train_input_fn = tf.estimator.inputs.numpy_input_fn(
x={"words": x_train}, # x_train is 2D numpy array of shape (26, 5)
y=y_train, # y_train is 1D panda series of length 26
batch_size=1000,
num_epochs=None,
shuffle=True)
classifier.train(input_fn=train_input_fn, steps=300)
I then try to save the model:
def serving_input_receiver_fn():
serialized_tf_example = tf.placeholder(dtype=tf.int64, shape=(None, 5), name='words')
receiver_tensors = {"predictor_inputs": serialized_tf_example}
features = {"words": tf.placeholder(tf.int64, shape=(None, 5))}
return tf.estimator.export.ServingInputReceiver(features, receiver_tensors)
full_model_dir = classifier.export_savedmodel(export_dir_base="E:/models/", serving_input_receiver_fn=serving_input_receiver_fn)
I have actually copied the serving_input_receiver_fn from this similar question. I don't understand exactly what is going on in that function. But this stores my model in E:/models/<some time stamp>.
I now try to load this saved model:
from tensorflow.contrib import predictor
classifier = predictor.from_saved_model("E:\\models\\<some time stamp>")
The models perfectly loaded. Hereafter, I am struck on how to use this classifier object to get predictions on new data. I have followed a guide here to achieve it but couldn't do it :(. Here is what I did:
predictions = classifier({'predictor_inputs': x_test})["output"] # x_test is 2D numpy array same like x_train in the training part
I get error as follows:
2019-01-10 12:43:38.603506: I tensorflow/core/platform/cpu_feature_guard.cc:141] Your CPU supports instructions that this TensorFlow binary was not compiled to use: AVX2
INFO:tensorflow:Restoring parameters from E:\models\1547101005\variables\variables
Traceback (most recent call last):
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\client\session.py", line 1334, in _do_call
return fn(*args)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\client\session.py", line 1319, in _run_fn
options, feed_dict, fetch_list, target_list, run_metadata)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\client\session.py", line 1407, in _call_tf_sessionrun
run_metadata)
tensorflow.python.framework.errors_impl.InvalidArgumentError: You must feed a value for placeholder tensor 'Placeholder' with dtype int64 and shape [?,5]
[[{{node Placeholder}} = Placeholder[dtype=DT_INT64, shape=[?,5], _device="/job:localhost/replica:0/task:0/device:CPU:0"]()]]
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "E:/ml_classif/tensorflow_bow_with_prob/load_model.py", line 85, in <module>
predictions = classifier({'predictor_inputs': x_test})["output"]
File "E:\ml_classif\venv\lib\site-packages\tensorflow\contrib\predictor\predictor.py", line 77, in __call__
return self._session.run(fetches=self.fetch_tensors, feed_dict=feed_dict)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\client\session.py", line 929, in run
run_metadata_ptr)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\client\session.py", line 1152, in _run
feed_dict_tensor, options, run_metadata)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\client\session.py", line 1328, in _do_run
run_metadata)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\client\session.py", line 1348, in _do_call
raise type(e)(node_def, op, message)
tensorflow.python.framework.errors_impl.InvalidArgumentError: You must feed a value for placeholder tensor 'Placeholder' with dtype int64 and shape [?,5]
[[node Placeholder (defined at E:\ml_classif\venv\lib\site-packages\tensorflow\contrib\predictor\saved_model_predictor.py:153) = Placeholder[dtype=DT_INT64, shape=[?,5], _device="/job:localhost/replica:0/task:0/device:CPU:0"]()]]
Caused by op 'Placeholder', defined at:
File "E:/ml_classif/tensorflow_bow_with_prob/load_model.py", line 82, in <module>
classifier = predictor.from_saved_model("E:\\models\\1547101005")
File "E:\ml_classif\venv\lib\site-packages\tensorflow\contrib\predictor\predictor_factories.py", line 153, in from_saved_model
config=config)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\contrib\predictor\saved_model_predictor.py", line 153, in __init__
loader.load(self._session, tags.split(','), export_dir)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\saved_model\loader_impl.py", line 197, in load
return loader.load(sess, tags, import_scope, **saver_kwargs)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\saved_model\loader_impl.py", line 350, in load
**saver_kwargs)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\saved_model\loader_impl.py", line 278, in load_graph
meta_graph_def, import_scope=import_scope, **saver_kwargs)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\training\saver.py", line 1696, in _import_meta_graph_with_return_elements
**kwargs))
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\framework\meta_graph.py", line 806, in import_scoped_meta_graph_with_return_elements
return_elements=return_elements)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\util\deprecation.py", line 488, in new_func
return func(*args, **kwargs)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\framework\importer.py", line 442, in import_graph_def
_ProcessNewOps(graph)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\framework\importer.py", line 234, in _ProcessNewOps
for new_op in graph._add_new_tf_operations(compute_devices=False): # pylint: disable=protected-access
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\framework\ops.py", line 3440, in _add_new_tf_operations
for c_op in c_api_util.new_tf_operations(self)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\framework\ops.py", line 3440, in <listcomp>
for c_op in c_api_util.new_tf_operations(self)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\framework\ops.py", line 3299, in _create_op_from_tf_operation
ret = Operation(c_op, self)
File "E:\ml_classif\venv\lib\site-packages\tensorflow\python\framework\ops.py", line 1770, in __init__
self._traceback = tf_stack.extract_stack()
InvalidArgumentError (see above for traceback): You must feed a value for placeholder tensor 'Placeholder' with dtype int64 and shape [?,5]
[[node Placeholder (defined at E:\ml_classif\venv\lib\site-packages\tensorflow\contrib\predictor\saved_model_predictor.py:153) = Placeholder[dtype=DT_INT64, shape=[?,5], _device="/job:localhost/replica:0/task:0/device:CPU:0"]()]]
It says that I have to feed value to the placeholder (I think the one defined in serving_input_receiver_fn). I have no idea how to do it without using a Session object of tensorflow.
Please feel free to ask for more information if required.

Answer 1

After somewhat vague understanding of serving_input_receiver_fn, I figured out that the features must not be a placeholder as it creates 2 placeholders (1 for serialized_tf_example and the other for features). I modified the function as follows (the changes is just for the features variable):
def serving_input_receiver_fn():
serialized_tf_example = tf.placeholder(dtype=tf.int64, shape=(None, 5), name='words')
receiver_tensors = {"predictor_inputs": serialized_tf_example}
features = {"words": tf.tile(serialized_tf_example, multiples=[1, 1])} # Changed this
return tf.estimator.export.ServingInputReceiver(features, receiver_tensors)
When I try to predict the output from the loaded model, I get no error now. It works! Only thing is that the output is incorrect (for which I am posting a new question :) ).