Log metric row after validation passes
Is your feature request related to a problem? Please describe.
metrics.csv file, used with test-tube Experiment, is pretty nice way to report some simple results. Unfortunately, logging gets invoked only after training steps. As a result, I can't get the last validation pass results in this file.
Describe the solution you'd like
Option to write metrics from validation_end in a file, similar to metrics.csv, as a Trainer parameter.
Describe alternatives you've considered
Logging directly in "validation_end" method, but I haven't found a way to get the context (Experiment, Trainer state) to enrich the information.
Perhaps some access to active Trainer from LightningModule functions, so we can control logging without global variables or duplicating this functionality.