Fix advantage calculation off-by-one error (#363) #445
+10
−10
Conversation
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
1 participant
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
Fixes #363
Changed buffer shapes from (segments, horizon) to (segments, horizon + 1). Now we store 65 states which gives us 64 full transitions instead of just 63.
Also changed the rollout loop from >= to > at line 300 so it actually collects that last transition.
Before this fix, advantages[:, -1] was always 0 and the last sample in every segment had broken gradients (pg_loss ≈ 0, entropy made policy random, value function got conservative updates).
Now all 64 samples get proper advantage calculations.
Closes #363