advanced deep-learning best practices validation_sample self validation_data[ ][ : activations self activations_model predict(validation_samplef open('activations_at_epoch_str(epochnpz'' 'np savez(factivationsf close(obtains the first input sample of the validation data saves arrays to disk this is all you need to know about callbacks--the rest is technical detailswhich you can easily look up now you're equipped to perform any sort of logging or preprogrammed intervention on keras model during training introduction to tensorboardthe tensorflow visualization framework to do good research or develop good modelsyou need richfrequent feedback about what' going on inside your models during your experiments that' the point of running experimentsto get information about how well model performs--as much information as possible making progress is an iterative processor loopyou start with an idea and express it as an experimentattempting to validate or invalidate your idea you run this experiment and process the information it generates this inspires your next idea the more iterations of this loop you're able to runthe more refined and powerful your ideas become keras helps you go from idea to experiment in the least possible timeand fast gpus can help you get from experiment to result as quickly as possible but what about processing the experiment resultsthat' where tensorboard comes in idea visualization frameworktensorboard deep-learning frameworkkeras results experiment infrastructure figure the loop of progress this section introduces tensorboarda browser-based visualization tool that comes packaged with tensorflow note that it' only available for keras models when you're using keras with the tensorflow backend the key purpose of tensorboard is to help you visually monitor everything that goes on inside your model during training if you're monitoring more information than just the model' final lossyou can develop clearer vision of what the model does and doesn' doand you can make progress more quickly tensorboard gives you access to several neat featuresall in your browserlicensed to