Woefully split logging concerns - How do I log the metrics I want?

[nervecenter]

I've been trying to grapple with systems such as CSVLogger, LearningRateMonitor, and the training_epoch_end() and validation_epoch_end() methods. Everything seems horribly split, to the point where LearningRateMonitor is passed in as a callback, while normal logger objects are passed in to the Trainer, and they can't talk to the LearningRateMonitor; the passed-in logger objects can't even access the learning rate. Not to mention that manually writing metrics to a logger versus passing logging parameters to a logging object cause them to write mangled and interspersed data to file, rendering the log files a nightmare (or even impossible) to interpret.

All I want to do is write a simple CSV. At the end of each epoch, after validation, I want to record four columns: The epoch number; the average training loss; the average validation loss; the learning rate.

That's it. I've been scouring the docs and it currently seems like it can't be done.

[Troublem1]

The learning rate monitor seems to act like a callback so try passing it into the callback hook in the trainer..

[Troublem1]

For your objective I propose you return both the train loss and Val loss at the training step and validation step. Find their averages in Validation at epoch end.
Add the results as a row to your dataframe with its 4 columns..

To get the learning rate at each epoch or step I propose using self.lr so you'd be able get the current learning rate being used at each step/epoch

[Troublem1]

Also you don't need to manually do all this ..you can simply use self.log() for both the training and Val averages