Question about padding in molecule collation/batching

[FarzanT]

Hello,
I am having some difficulty understanding how maximum pad lengths are calculated in the collator functions:

Uni-Mol/unimol_plus/unimol_plus/data/pcq_dataset.py

Lines 181 to 182 in 7394647

	max_node_num = max([item["atom_mask"].shape[0] for item in items])
	max_node_num = (max_node_num + 1 + 3) // 4 * 4 - 1

The way it's currently calculated, we end up adding a padded element to all feature vectors even when the batch size (or len(items)) is 1. Perhaps I'm wrong, but would you explain why the above formula is used?

Thank you!