More flexible paths for saving tensorboard data

[bobkemp]

🚀 Feature

I'd like more flexibility in the directory hierarchy used for writing tensorboard data.
Specifically, I want to make the experiment-name directory optional, removing one level in the hierarchy.

Also I'd like to be able to specify the name of the version directory. Currently it is "version_N" but if the constructor version parameter is a string, I think it could just directly use that.

Motivation

You could specify the version on the command line or generate it from the current datetime, which I find more meaningful than "version_73". Likewise if the tensorboard data is not going to be preserved, it's much more readable in the tensorboard gui to skip the experiment name.

Pitch

I have a branch with working code + tests

https://github.com/bobkemp/pytorch-lightning/tree/tensorboard-path-generalisation

Alternatives

None

Additional context

[williamFalcon]

@bobkemp could you post examples and use cases of what you mean? also, you can submit a PR to make the changes easier to see.

[bobkemp]

Here's the directory layout you could have and how it appears in TensorBoard.
I think the change also cleans up the code a little, removing duplication.

Without experiments directory:
TensorBoardLogger(tensorboard_dir, name="")

checkpoints/version_0
checkpoints/version_0/events.out.tfevents.1581113035.glia.8401.0
checkpoints/version_0/meta_tags.csv

Without experiments directory and with explicitly named version directory:
TensorBoardLogger(tensorboard_dir, name="", version="2020-02-07-220525")
checkpoints/2020-02-07-220525
checkpoints/2020-02-07-220525/events.out.tfevents.1581113127.glia.8438.0
checkpoints/2020-02-07-220525/meta_tags.csv

Current code:
TensorBoardLogger(tensorboard_dir)
checkpoints/default
checkpoints/default/version_0
checkpoints/default/version_0/events.out.tfevents.1581112657.glia.8299.0
checkpoints/default/version_0/meta_tags.csv
checkpoints/default/version_1
checkpoints/default/version_1/events.out.tfevents.1581112777.glia.8341.0
checkpoints/default/version_1/meta_tags.csv

[bobkemp]

PR #804