Issue with fetching raw documents

[waylight3]

from pyserini.search.lucene import LuceneSearcher

searcher = LuceneSearcher.from_prebuilt_index('beir-v1.0.0-nfcorpus.splade-pp-ed')
doc = searcher.doc('MED-10')
print(doc.contents()) # None
print(doc.raw()) # None

When attempting to fetch a raw document using the beir-v1.0.0-nfcorpus.splade-pp-ed index, the function returns None.
However, when I use the beir-v1.0.0-nfcorpus.flat index, it returns the correct document as expected.
Could you please clarify if this issue is related to the prebuilt index itself or if it might be due to a bug in the library?
Any guidance or suggestions to resolve this matter would be greatly appreciated.

[lintool]

Hi @waylight3 this is the expected behavior. This is because once a document is encoded by SPLADE, it is no longer human-readable, so we've decided not to store them in the prebuilt indexes. Getting the actual human-readable text from the flat index is indeed the preferred approach.

[waylight3]

Thank you for the kind answer! Then, can I fecth SPLADE encodings from this index?

[lintool]

You can download the SPLADE encodings from here: https://github.com/castorini/anserini?tab=readme-ov-file#%EF%B8%8F-end-to-end-regression-experiments under "BEIR (v1.0.0) Regressions" tab.