Create README.md

README.md

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+---
+pretty_name: MS MARCO v1 Passage multivector embeddings (ColBERTv2)
+task_categories: [text-retrieval]
+tags: [late-interaction, colbert, multivector, msmarco]
+---
+
+# MS MARCO v1 Passage, ColBERTv2
+
+Token-level (late-interaction) ColBERTv2 embeddings of the MS MARCO v1 passage collection and the dev/small queries.
+
+## Source
+- Collection: MS MARCO v1 passage (`ir_datasets` `msmarco-passage`), 8,841,823 passages
+- Queries: dev/small, 6,980 queries and 7,437 qrels (`msmarco-passage/dev/small`)
+- Document order: passage id order (row *i* is pid *i*)
+
+## Encoding
+- Model: ColBERTv2 (`colbert-ir/colbertv2.0`, BERT-base-uncased tokenizer)
+- Documents start with `[CLS]` and the ColBERT `[D]` marker (token id 2)
+- Queries: always 32 vectors (`[MASK]` expansion, no zero padding)
+- Vectors: 128-d, L2-normalized
+- **Not recorded:** exact checkpoint revision, encoding library, document length cap (the longest document has 300 vectors), and whether punctuation was dropped
+
+## Statistics
+| | |
+|---|---|
+| Token vectors (N) | 597,909,919 |
+| Avg vectors per document | 67.6 (min 4, max 300) |
+| Vectors per query | 32 |
+
+## Files
+| File | dtype | Shape | Content |
+|---|---|---|---|
+| `documents.npy` | uint16 (`<u2`) | `[597909919, 128]` | Raw float16 bit patterns stored as uint16. Read with `.view(np.float16)` |
+| `doclens.npy` | int32 | `[8841823]` | Vectors per document; `sum == N` |
+| `token_ids_per_token.npy` | int64 | `[597909919]` | Input token id of each row of `documents.npy` |
+| `doc_ids.npy` | int64 | `[8841823]` | MS MARCO pid (equals the row index) |
+| `queries.npy` | float32 | `[6980, 32, 128]` | Query vectors |
+| `queries_ids.npy` | int64 | `[6980]` | MS MARCO qid of each query |
+
+Document ids are MS MARCO passage ids and equal the row index: row *i* of `doclens.npy` is passage *i*.
+
+`documents.npy` stores float16 values as their raw 16-bit patterns, with dtype uint16.
+In numpy, read it with `np.load("documents.npy", mmap_mode="r").view(np.float16)`.
+
+## Relevance judgments
+The official MS MARCO passage dev/small qrels (`qrels.dev.small.tsv`): 7,437 relevant
+query-passage pairs over the 6,980 queries, all with relevance 1 (`ir_datasets` `msmarco-passage/dev/small`).
+Standard metric: MRR@10 (`RR@10` in `ir_measures`).