mirror of
https://github.com/huggingface/lerobot.git
synced 2026-06-17 16:27:04 +00:00
Pepijn
6fa495c6b0
Add a sampler that never materializes frame indices: it stores only per-episode boundaries (numpy, a few bytes per episode) and maps logical positions to frame indices on the fly with searchsorted. Shuffling uses a seeded Feistel permutation over [0, num_frames) (cycle-walking to the exact domain), so the data order is a pure function of (seed, epoch): - no RNG state to synchronize across distributed ranks, - constant memory and zero epoch-boundary cost at any dataset size, - O(1) seek to any position, enabling sample-exact resume. Opt in with --deterministic_sampler=true. On resume, lerobot-train maps the checkpointed step back to (epoch, start_index) via compute_sampler_state and continues at the exact sample where the run left off (up to accelerate's even_batches padding at epoch boundaries). The shuffle is pseudo-random rather than a true uniform permutation, the standard trade-off in large-scale training loaders. Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>