Related
I want to create an MLP based custom CNN model (multi-scaled) consists of several parallel small networks (capsules). These simple small networks are instantiated as a custom layer (conv2d->Flatten->Dense) for each convolution scale i.e. 3x3, 5x5. The purpose of these capsule networks is to generate intermediate loss consciousness to reduce overall global loss using the CNN model. I have written some sketchy codes but I'm not able to write the correct code for computing local loss using these capsules. Here's the code:
from tensorflow.keras import layers
import tensorflow as tf
from tensorflow.keras.datasets import mnist
from tensorflow.keras.layers import Layer
class capsule(tf.keras.layers.Layer):
def __init__(self):
super(capsule, self).__init__()
self.loss_fn = tf.keras.losses.CategoricalCrossentropy(from_logits=True)
self.Flatten = tf.keras.layers.Flatten()
self.conv2D = tf.keras.layers.Conv2D(3,3,(1,1),padding='same', activation='relu',name="LocalLoss3x3")
self.classifier = tf.keras.layers.Dense(10,activation='softmax', name='capsule3Output')
def call(self, inputs):
x=self.conv2D(inputs)
x=self.Flatten(x)
x=self.classifier(x)
pred=self(x_train)
loss=self.loss_fn(pred,y_train)
#self.add_loss(self.rate * tf.reduce_sum(tf.square(inputs)))
return loss, x
(x_train, y_train), (x_test, y_test)= mnist.load_data()
from tensorflow.keras import layers
class SparseMLP(tf.keras.models.Model):
def __init__(self, output_dim):
super(SparseMLP, self).__init__()
self.dense_1 = layers.Dense(1, activation=tf.nn.relu)
self.capsule = capsule()
self.dense_2 = layers.Dense(output_dim)
def call(self, inputs):
x = self.dense_1(inputs)
loss,x = self.capsule(inputs)
return self.dense_2(x)
mlp = SparseMLP(10)
#x_train=x_train.reshape(-1,28,28,1)
y = mlp(x_train)
To include a loss within a layer , you can use add_loss function of tf.keras.layers.Layer class. This fucntion takes a loss value and adds it up to the global loss function define in compile function.
you can call self.add_loss(loss_value) from inside the call method of a custom
layer.Losses added in this way get added to the "main" loss during training
(the one passed to compile()).
So to make ur model consider the losses from intermediate layer , you should uncomment the add_loss fn , and then train the model in usual way that you train.
Please mind that it is totally fine to not declare a "main" loss in the compile function as there already is a loss that ur defining in your layer class.
Note that when you pass losses via add_loss(), it becomes possible to call compile() without a loss function, since the model already has a loss to minimize.
Please note that call function of SparseMLP model , should look like this:
x = self.dense_1(inputs)
# i dunno if u desire to do this, that is pass inputs in capsule
# instead of x.Currently the output from dense_1 is not used at all .
# so keep in mind to make sure ur passing proper inputs to layers.
# and u do not have to call loss here as it will tracked internally by
# keras.
x = self.capsule(inputs)
return self.dense_2(x)
So running your model like below should do the trick:
model.compile(loss = "define ur main loss is there is" , metrics = "define ur metrics")
model.fit(x = train_inst , y = train_targets)
Using the keras subclass API it is easy enough to add a a batch normalization layer however the layer.losses list always appears empty. What is the correct method of including in the train loss when doing tape.gradient(loss, lossmodel.trainable_variables) where lossmodel is some separate keras subclass model defining a more complicated loss function that must include the gradient losses?
For example, this is minimal model with ONLY the batch norm layer. It has no loss AFAIK
class M(tf.keras.Model):
def __init__(self, axis):
super().__init__()
self.layer = tf.keras.layers.BatchNormalization(axis=axis, scale=False, center=True, virtual_batch_size=1, input_shape=(6,))
def call(self, x):
out = self.layer(x)
return out
m = M(1)
In [77]: m.layer.losses
Out[77]: []
I would like to save the best model in Keras based on auc and I have this code:
def MyMetric(yTrue, yPred):
auc = tf.metrics.auc(yTrue, yPred)
return auc
best_model = [ModelCheckpoint(filepath='best_model.h5', monitor='MyMetric', save_best_only=True)]
train_history = model.fit([train_x],
[train_y], batch_size=batch_size, epochs=epochs, validation_split=0.05,
callbacks=best_model, verbose = 2)
SO my model runs nut I get this warning:
RuntimeWarning: Can save best model only with MyMetric available, skipping.
'skipping.' % (self.monitor), RuntimeWarning)
It would be great if any can tell me this is the right way to do it and if not what should I do?
You have to pass the Metric you want to monitor to model.compile.
https://keras.io/metrics/#custom-metrics
model.compile(loss='categorical_crossentropy', optimizer='adam', metrics=[MyMetric])
Also, tf.metrics.auc returns a tuple containing the tensor and update_op. Keras expects the custom metric function to return only a tensor.
def MyMetric(yTrue, yPred):
import tensorflow as tf
auc = tf.metrics.auc(yTrue, yPred)
return auc[0]
After this step, you will get errors about uninitialized values. Please see these threads:
https://github.com/keras-team/keras/issues/3230
How to compute Receiving Operating Characteristic (ROC) and AUC in keras?
You can define a custom metric that calls tensorflow to compute AUROC in the following way:
def as_keras_metric(method):
import functools
from keras import backend as K
import tensorflow as tf
#functools.wraps(method)
def wrapper(self, args, **kwargs):
""" Wrapper for turning tensorflow metrics into keras metrics """
value, update_op = method(self, args, **kwargs)
K.get_session().run(tf.local_variables_initializer())
with tf.control_dependencies([update_op]):
value = tf.identity(value)
return value
return wrapper
#as_keras_metric
def AUROC(y_true, y_pred, curve='ROC'):
return tf.metrics.auc(y_true, y_pred, curve=curve)
You then need to compile your model with this metric:
model.compile(loss=train_loss, optimizer='adam', metrics=['accuracy',AUROC])
Finally: Checkpoint the model in the following way:
model_checkpoint = keras.callbacks.ModelCheckpoint(path_to_save_model, monitor='val_AUROC',
verbose=0, save_best_only=True,
save_weights_only=False, mode='auto', period=1)
Be careful though: I believe the Validation AUROC is calculated batch wise and averaged; so might give some errors with checkpointing. A good idea might be to verify after model training finishes that the AUROC of the predictions of the trained model (computed with sklearn.metrics) matches what Tensorflow reports while training and checkpointing
Assuming you use TensorBoard, then you have a historical record—in the form of tfevents files—of all your metric calculations, for all your epochs; then a tf.keras.callbacks.Callback is what you want.
I use tf.keras.callbacks.ModelCheckpoint with save_freq: 'epoch' to save—as an h5 file or tf file—the weights for each epoch.
To avoid filling the hard-drive with model files, write a new Callback—or extend the ModelCheckpoint class's—on_epoch_end implementation:
def on_epoch_end(self, epoch, logs=None):
super(DropWorseModels, self).on_epoch_end(epoch, logs)
if epoch < self._keep_best:
return
model_files = frozenset(
filter(lambda filename: path.splitext(filename)[1] == SAVE_FORMAT_WITH_SEP,
listdir(self._model_dir)))
if len(model_files) < self._keep_best:
return
tf_events_logs = tuple(islice(log_parser(tfevents=path.join(self._log_dir,
self._split),
tag=self.monitor),
0,
self._keep_best))
keep_models = frozenset(map(self._filename.format,
map(itemgetter(0), tf_events_logs)))
if len(keep_models) < self._keep_best:
return
it_consumes(map(lambda filename: remove(path.join(self._model_dir, filename)),
model_files - keep_models))
Appendix (imports and utility function implementations):
from itertools import islice
from operator import itemgetter
from os import path, listdir, remove
from collections import deque
import tensorflow as tf
from tensorflow.core.util import event_pb2
def log_parser(tfevents, tag):
values = []
for record in tf.data.TFRecordDataset(tfevents):
event = event_pb2.Event.FromString(tf.get_static_value(record))
if event.HasField('summary'):
value = event.summary.value.pop(0)
if value.tag == tag:
values.append(value.simple_value)
return tuple(sorted(enumerate(values), key=itemgetter(1), reverse=True))
it_consumes = lambda it, n=None: deque(it, maxlen=0) if n is None \
else next(islice(it, n, n), None)
SAVE_FORMAT = 'h5'
SAVE_FORMAT_WITH_SEP = '{}{}'.format(path.extsep, SAVE_FORMAT)
For completeness, the rest of the class:
class DropWorseModels(tf.keras.callbacks.Callback):
"""
Designed around making `save_best_only` work for arbitrary metrics
and thresholds between metrics
"""
def __init__(self, model_dir, monitor, log_dir, keep_best=2, split='validation'):
"""
Args:
model_dir: directory to save weights. Files will have format
'{model_dir}/{epoch:04d}.h5'.
split: dataset split to analyse, e.g., one of 'train', 'test', 'validation'
monitor: quantity to monitor.
log_dir: the path of the directory where to save the log files to be
parsed by TensorBoard.
keep_best: number of models to keep, sorted by monitor value
"""
super(DropWorseModels, self).__init__()
self._model_dir = model_dir
self._split = split
self._filename = 'model-{:04d}' + SAVE_FORMAT_WITH_SEP
self._log_dir = log_dir
self._keep_best = keep_best
self.monitor = monitor
This has the added advantage of being able to save and delete multiple model files in a single Callback. You can easily extend with different thresholding support, e.g., to keep all model files with an AUC in threshold OR TP, FP, TN, FN within threshold.
Inspired by tf.keras.Model subclassing I created custom model.
I can train it and get successfull results, but I can't save it.
I use python3.6 with tensorflow v1.10 (or v1.9)
Minimal complete code example here:
import tensorflow as tf
from tensorflow.keras.datasets import mnist
class Classifier(tf.keras.Model):
def __init__(self):
super().__init__(name="custom_model")
self.batch_norm1 = tf.layers.BatchNormalization()
self.conv1 = tf.layers.Conv2D(32, (7, 7))
self.pool1 = tf.layers.MaxPooling2D((2, 2), (2, 2))
self.batch_norm2 = tf.layers.BatchNormalization()
self.conv2 = tf.layers.Conv2D(64, (5, 5))
self.pool2 = tf.layers.MaxPooling2D((2, 2), (2, 2))
def call(self, inputs, training=None, mask=None):
x = self.batch_norm1(inputs)
x = self.conv1(x)
x = tf.nn.relu(x)
x = self.pool1(x)
x = self.batch_norm2(x)
x = self.conv2(x)
x = tf.nn.relu(x)
x = self.pool2(x)
return x
if __name__ == '__main__':
(x_train, y_train), (x_test, y_test) = mnist.load_data()
x_train = x_train.reshape(*x_train.shape, 1)[:1000]
y_train = y_train.reshape(*y_train.shape, 1)[:1000]
x_test = x_test.reshape(*x_test.shape, 1)
y_test = y_test.reshape(*y_test.shape, 1)
y_train = tf.keras.utils.to_categorical(y_train)
y_test = tf.keras.utils.to_categorical(y_test)
model = Classifier()
inputs = tf.keras.Input((28, 28, 1))
x = model(inputs)
x = tf.keras.layers.Flatten()(x)
x = tf.keras.layers.Dense(10, activation="sigmoid")(x)
model = tf.keras.Model(inputs=inputs, outputs=x)
model.compile(optimizer="adam", loss="binary_crossentropy", metrics=["accuracy"])
model.fit(x_train, y_train, epochs=1, shuffle=True)
model.save("./my_model")
Error message:
1000/1000 [==============================] - 1s 1ms/step - loss: 4.6037 - acc: 0.7025
Traceback (most recent call last):
File "/home/user/Data/test/python/mnist/mnist_run.py", line 62, in <module>
model.save("./my_model")
File "/home/user/miniconda3/envs/ml3.6/lib/python3.6/site-packages/tensorflow/python/keras/engine/network.py", line 1278, in save
save_model(self, filepath, overwrite, include_optimizer)
File "/home/user/miniconda3/envs/ml3.6/lib/python3.6/site-packages/tensorflow/python/keras/engine/saving.py", line 101, in save_model
'config': model.get_config()
File "/home/user/miniconda3/envs/ml3.6/lib/python3.6/site-packages/tensorflow/python/keras/engine/network.py", line 1049, in get_config
layer_config = layer.get_config()
File "/home/user/miniconda3/envs/ml3.6/lib/python3.6/site-packages/tensorflow/python/keras/engine/network.py", line 1028, in get_config
raise NotImplementedError
NotImplementedError
Process finished with exit code 1
I looked into the error line and found out that get_config method checks self._is_graph_network
Do anybody deal with this problem?
Thanks!
Update 1:
On the keras 2.2.2 (not tf.keras)
Found comment (for model saving)
file: keras/engine/network.py
Function: get_config
# Subclassed networks are not serializable
# (unless serialization is implemented by
# the author of the subclassed network).
So, obviously it won't work...
I wonder, why don't they point it out in the documentation (Like: "Use subclassing without ability to save!")
Update 2:
Found in keras documentation:
In subclassed models, the model's topology is defined as Python code
(rather than as a static graph of layers). That means the model's
topology cannot be inspected or serialized. As a result, the following
methods and attributes are not available for subclassed models:
model.inputs and model.outputs.
model.to_yaml() and model.to_json()
model.get_config() and model.save().
So, there is no way to save model by using subclassing.
It's possible to only use Model.save_weights()
TensorFlow 2.2
Thanks for #cal for noticing me that the new TensorFlow has supported saving the custom models!
By using model.save to save the whole model and by using load_model to restore previously stored subclassed model. The following code snippets describe how to implement them.
class ThreeLayerMLP(keras.Model):
def __init__(self, name=None):
super(ThreeLayerMLP, self).__init__(name=name)
self.dense_1 = layers.Dense(64, activation='relu', name='dense_1')
self.dense_2 = layers.Dense(64, activation='relu', name='dense_2')
self.pred_layer = layers.Dense(10, name='predictions')
def call(self, inputs):
x = self.dense_1(inputs)
x = self.dense_2(x)
return self.pred_layer(x)
def get_model():
return ThreeLayerMLP(name='3_layer_mlp')
model = get_model()
# Save the model
model.save('path_to_my_model',save_format='tf')
# Recreate the exact same model purely from the file
new_model = keras.models.load_model('path_to_my_model')
See: Save and serialize models with Keras - Part II: Saving and Loading of Subclassed Models
TensorFlow 2.0
TL;DR:
do not use model.save() for custom subclass keras model;
use save_weights() and load_weights() instead.
With the help of the Tensorflow Team, it turns out the best practice of saving a Custom Sub-Class Keras Model is to save its weights and load it back when needed.
The reason that we can not simply save a Keras custom subclass model is that it contains custom codes, which can not be serialized safely. However, the weights can be saved/loaded when we have the same model structure and custom codes without any problem.
There has a great tutorial written by Francois Chollet who is the author of Keras, for how to save/load Sequential/Functional/Keras/Custom Sub-Class Models in Tensorflow 2.0 in Colab at here. In Saving Subclassed Models section, it said that:
Sequential models and Functional models are datastructures that represent a DAG of layers. As such, they can be safely serialized and deserialized.
A subclassed model differs in that it's not a datastructure, it's a
piece of code. The architecture of the model is defined via the body
of the call method. This means that the architecture of the model
cannot be safely serialized. To load a model, you'll need to have
access to the code that created it (the code of the model subclass).
Alternatively, you could be serializing this code as bytecode (e.g.
via pickling), but that's unsafe and generally not portable.
This will be fixed in an upcoming release according to the 1.13 pre-release patch notes:
Keras & Python API:
Subclassed Keras models can now be saved through tf.contrib.saved_model.save_keras_model.
EDIT:
It seems this is not quite as finished as the notes suggest. The docs for that function for v1.13 state:
Model limitations: - Sequential and functional models can always be saved. - Subclassed models can only be saved when serving_only=True. This is due to the current implementation copying the model in order to export the training and evaluation graphs. Because the topology of subclassed models cannot be determined, the subclassed models cannot be cloned. Subclassed models will be entirely exportable in the future.
Tensorflow 2.1 allows to save subclassed models with SavedModel format
From my beginning using Tensorflow, i was always a fan of Model Subclass, i feel this way of build models more pythonic and collaborative friendly. But saving the model was always a point of pain with this approach.
Recently i started to update my knowledge and reach to the following information that seems to be True for Tensorflow 2.1:
Subclassed Models
I found this
Second approach is by using model.save to save whole model and by
using load_model to restore previously stored subclassed model.
This last saves the model, the weight and other stuff into a SavedModel file
And by last the confirmation:
Saving custom objects:
If you are using the SavedModel format, you can
skip this section. The key difference between HDF5 and SavedModel is
that HDF5 uses object configs to save the model architecture, while
SavedModel saves the execution graph. Thus, SavedModels are able to
save custom objects like subclassed models and custom layers without
requiring the orginal code.
I tested this personally, and efectively, model.save() for subclassed models generate a SavedModel save. There is no more need for use model.save_weights() or related functions, they now are more for specific usecases.
This is suposed to be the end of this painful path for all of us interested in Model Subclassing.
I found a way to solve it. Create a new model and load the weights from the saved .h5 model. This way is not preferred, but it works with keras 2.2.4 and tensorflow 1.12.
class MyModel(keras.Model):
def __init__(self, inputs, *args, **kwargs):
outputs = func(inputs)
super(MyModel, self).__init__( inputs=inputs, outputs=outputs, *args, **kwargs)
def get_model():
return MyModel(inputs, *args, **kwargs)
model = get_model()
model.save(‘file_path.h5’)
model_new = get_model()
model_new.compile(optimizer=optimizer, loss=loss, metrics=metrics)
model_new.load_weights(‘file_path.h5’)
model_new.evaluate(x_test, y_test, **kwargs)
UPDATE: Jul 20
Recently I also tried to create my subclassed layers and model. Write your own get_config() function might be difficult. So I used model.save_weights(path_to_model_weights) and model.load_weights(path_to_model_weights). When you want to load the weights, remember to create the model with the same architecture than do model.load_weights(). See the tensorflow guide for more details.
Old Answer (Still correct)
Actually, tensorflow document said:
In order to save/load a model with custom-defined layers, or a subclassed model, you should overwrite the get_config and optionally from_config methods. Additionally, you should use register the custom object so that Keras is aware of it.
For example:
class Linear(keras.layers.Layer):
def __init__(self, units=32, **kwargs):
super(Linear, self).__init__(**kwargs)
self.units = units
def build(self, input_shape):
self.w = self.add_weight(
shape=(input_shape[-1], self.units),
initializer="random_normal",
trainable=True,
)
self.b = self.add_weight(
shape=(self.units,), initializer="random_normal", trainable=True
)
def call(self, inputs):
return tf.matmul(inputs, self.w) + self.b
def get_config(self):
config = super(Linear, self).get_config()
config.update({"units": self.units})
return config
layer = Linear(64)
config = layer.get_config()
print(config)
new_layer = Linear.from_config(config)
The output is:
{'name': 'linear_8', 'trainable': True, 'dtype': 'float32', 'units': 64}
You can play with this simple code. For example, in function "get_config()", remove config.update(), see what's going on. See this and this for more details. These are the Keras guide on tensorflow website.
use model.predict before tf.saved_model.save
Actually recreating the model with
keras.models.load_model('path_to_my_model')
didn't work for me
First we have to save_weights from the built model
model.save_weights('model_weights', save_format='tf')
Then
we have to initiate a new instance for the subclass Model then compile and train_on_batch with one record and load_weights of built model
loaded_model = ThreeLayerMLP(name='3_layer_mlp')
loaded_model.compile(optimizer="adam", loss="binary_crossentropy", metrics=["accuracy"])
loaded_model.train_on_batch(x_train[:1], y_train[:1])
loaded_model.load_weights('model_weights')
This work perfectly in TensorFlow==2.2.0
I added a callback to decay the learning rate:
keras.callbacks.ReduceLROnPlateau(monitor='val_loss', factor=0.5, patience=100,
verbose=0, mode='auto',epsilon=0.00002, cooldown=20, min_lr=0)
Here is my tensorboard callback:
keras.callbacks.TensorBoard(log_dir='./graph/rank{}'.format(hvd.rank()), histogram_freq=10, batch_size=FLAGS.batch_size,
write_graph=True, write_grads=True, write_images=False)
I want to make sure the learning rate scheduler has kicked in during training, so I want to output the learning rate onto tensorboard. But I can not find where I can set it.
I also checked the optimizer api, but no luck.
keras.optimizers.Adam(lr=0.001, beta_1=0.9, beta_2=0.999, epsilon=None, decay=0.0, amsgrad=False)
How can I output the learning rate to tensorboad?
According to the author of Keras, the proper way is to subclass the TensorBoard callback:
from keras import backend as K
from keras.callbacks import TensorBoard
class LRTensorBoard(TensorBoard):
# add other arguments to __init__ if you need
def __init__(self, log_dir, **kwargs):
super().__init__(log_dir=log_dir, **kwargs)
def on_epoch_end(self, epoch, logs=None):
logs = logs or {}
logs.update({'lr': K.eval(self.model.optimizer.lr)})
super().on_epoch_end(epoch, logs)
Then pass it as part of the callbacks argument to model.fit (credit Finncent Price):
model.fit(x=..., y=..., callbacks=[LRTensorBoard(log_dir="/tmp/tb_log")])
Note that with the current nightly version of tf (2.5 - probably earlier) learning rates using LearningRateSchedule are automatically added to tensorboard's logs. The following solution is only necessary if you're adapting the learning rate some other way - e.g. via ReduceLROnPlateau or LearningRateScheduler (different to LearningRateSchedule) callbacks.
While extending tf.keras.callbacks.TensorBoard is a viable option, I prefer composition over subclassing.
class LearningRateLogger(tf.keras.callbacks.Callback):
def __init__(self):
super().__init__()
self._supports_tf_logs = True
def on_epoch_end(self, epoch, logs=None):
if logs is None or "learning_rate" in logs:
return
logs["learning_rate"] = self.model.optimizer.lr
This allows us to compose multiple similar callbacks, and use the logged learning rate in multiple other callbacks (e.g. if you add a CSVLogger it should also write the learning rate values to file).
Then in model.fit
model.fit(
callbacks=[
LearningRateLogger(),
# other callbacks that update `logs`
tf.keras.callbacks.TensorBoard(path),
# other callbacks that use updated logs, e.g. CSVLogger
],
**kwargs
)
You gave the optimizer's code twice, instead of TensorBoard Callback. Anyway, I didn`t find the way to display the learning rate on TensorBoard.
I am plotting it after the training finished, taking data from History object:
nb_epoch = len(history1.history['loss'])
learning_rate=history1.history['lr']
xc=range(nb_epoch)
plt.figure(3,figsize=(7,5))
plt.plot(xc,learning_rate)
plt.xlabel('num of Epochs')
plt.ylabel('learning rate')
plt.title('Learning rate')
plt.grid(True)
plt.style.use(['seaborn-ticks'])
The chart looks like this:
LR plot
Sorry, that is not exactly what you are asking about, but perhaps could help.
class XTensorBoard(TensorBoard):
def on_epoch_begin(self, epoch, logs=None):
# get values
lr = float(K.get_value(self.model.optimizer.lr))
decay = float(K.get_value(self.model.optimizer.decay))
# computer lr
lr = lr * (1. / (1 + decay * epoch))
K.set_value(self.model.optimizer.lr, lr)
def on_epoch_end(self, epoch, logs=None):
logs = logs or {}
logs['lr'] = K.get_value(self.model.optimizer.lr)
super().on_epoch_end(epoch, logs)
callbacks_list = [XTensorBoard('./logs')]
model.fit(X_train, y_train, validation_data=(X_test, y_test), epochs=20, batch_size=32, verbose=2, callbacks=callbacks_list)
lr curve in tensorboard
For tensorflor 2.5 if you have some custom Learning Rate Scheduler:
class LearningRateLogger(tf.keras.callbacks.Callback):
def __init__(self, log_dir):
super().__init__()
self._supports_tf_logs = True
self.log_dir = log_dir
def set_model(self, model):
self.model = model
self.sess = tf.compat.v1.keras.backend.get_session()
self.writer = tf.summary.create_file_writer(self.log_dir)
def on_epoch_end(self, epoch, logs=None):
if logs is None or "learning_rate" in logs:
return
logs["learning_rate"] = self.model.optimizer.lr
logs.update({'learning_rate': self.model.optimizer.lr})
self._write_logs(logs, epoch)
def _write_logs(self, logs, index):
with self.writer.as_default():
for name, value in logs.items():
if name in ['batch', 'size']:
continue
if isinstance(value, np.ndarray):
tf.summary.scalar(name, value.item(), step=index)
else:
tf.summary.scalar(name, value, step=index)
self.writer.flush()
Then for calling the callback in your model.fit:
model.fit(x=..., y=..., callbacks=[LearningRateLogger(log_dir="/path/to/folder/where/tensorboard/is/logging")])