[keras] How do I use the Tensorboard callback of Keras?

Create the Tensorboard callback:

from keras.callbacks import TensorBoard
from datetime import datetime
logDir = "./Graph/" + datetime.now().strftime("%Y%m%d-%H%M%S") + "/"
tb = TensorBoard(log_dir=logDir, histogram_freq=2, write_graph=True, write_images=True, write_grads=True)

Pass the Tensorboard callback to the fit call:

history = model.fit(X_train, y_train, epochs=200, callbacks=[tb])

When running the model, if you get a Keras error of

"You must feed a value for placeholder tensor"

try reseting the Keras session before the model creation by doing:

import keras.backend as K
K.clear_session()