> ## Documentation Index
> Fetch the complete documentation index at: https://docs.lancedb.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Oxford-IIIT Pet

> A Lance-formatted version of the Oxford-IIIT Pet dataset — 7,390 cat and dog photos across 37 breeds — sourced from pcuenq/oxford-pets. Each row carries the inline JPEG bytes, the breed name, a species flag distinguishing cats from dogs, and a…

<Card title="View on Hugging Face" icon="https://mintcdn.com/lancedb-bcbb4faf/6L0IRVkfdlgMU1Pw/static/assets/logo/huggingface-logo.svg?fit=max&auto=format&n=6L0IRVkfdlgMU1Pw&q=85&s=da940a105a40440f0cd1224d3fa4ae52" href="https://huggingface.co/datasets/lance-format/oxford-pets-lance" width="640" height="640" data-path="static/assets/logo/huggingface-logo.svg">
  Source dataset card and downloadable files for `lance-format/oxford-pets-lance`.
</Card>

A Lance-formatted version of the [Oxford-IIIT Pet](https://www.robots.ox.ac.uk/~vgg/data/pets/) dataset — 7,390 cat and dog photos across 37 breeds — sourced from [`pcuenq/oxford-pets`](https://huggingface.co/datasets/pcuenq/oxford-pets). Each row carries the inline JPEG bytes, the breed name, a species flag distinguishing cats from dogs, and a cosine-normalized CLIP image embedding, all available directly from the Hub at `hf://datasets/lance-format/oxford-pets-lance/data`.

## Key features

* **Inline JPEG bytes** in the `image` column — no sidecar files, no image folders.
* **Pre-computed CLIP image embeddings** (`image_emb`, OpenCLIP `ViT-B-32`, 512-dim, cosine-normalized) with a bundled `IVF_PQ` index for similarity search.
* **Both breed and species labels** (`label_name`, `is_dog`) so a query can target a specific breed, all dogs, or all cats by stacking simple predicates.
* **Bitmap indices on both label columns** make species- and breed-based curation a cheap predicate rather than a full scan.

## Splits

| Split         | Rows  | Notes                                                                                                                                   |
| ------------- | ----- | --------------------------------------------------------------------------------------------------------------------------------------- |
| `train.lance` | 7,390 | The `pcuenq/oxford-pets` source mirror ships a single split; the canonical Oxford-IIIT trainval/test partition is not pre-applied here. |

## Schema

| Column       | Type                            | Notes                                                                            |
| ------------ | ------------------------------- | -------------------------------------------------------------------------------- |
| `id`         | `int64`                         | Row index within split (natural join key for merges)                             |
| `image`      | `large_binary`                  | Inline JPEG bytes (quality 92)                                                   |
| `label_name` | `string`                        | One of 37 breeds, underscore-spaced (`british_shorthair`, `golden_retriever`, …) |
| `is_dog`     | `bool`                          | `true` for dog breeds, `false` for cat breeds                                    |
| `path`       | `string?`                       | Original filename from the source dataset                                        |
| `image_emb`  | `fixed_size_list<float32, 512>` | OpenCLIP `ViT-B-32` image embedding (cosine-normalized)                          |

## Pre-built indices

* `IVF_PQ` on `image_emb` — vector similarity search (cosine)
* `BITMAP` on `label_name` — fast lookup by breed
* `BITMAP` on `is_dog` — fast species filter

## Why Lance?

1. **Blazing Fast Random Access**: Optimized for fetching scattered rows, making it ideal for random sampling, real-time ML serving, and interactive applications without performance degradation.
2. **Native Multimodal Support**: Store text, embeddings, and other data types together in a single file. Large binary objects are loaded lazily, and vectors are optimized for fast similarity search.
3. **Native Index Support**: Lance comes with fast, on-disk, scalable vector and FTS indexes that sit right alongside the dataset on the Hub, so you can share not only your data but also your embeddings and indexes without your users needing to recompute them.
4. **Efficient Data Evolution**: Add new columns and backfill data without rewriting the entire dataset. This is perfect for evolving ML features, adding new embeddings, or introducing moderation tags over time.
5. **Versatile Querying**: Supports combining vector similarity search, full-text search, and SQL-style filtering in a single query, accelerated by on-disk indexes.
6. **Data Versioning**: Every mutation commits a new version; previous versions remain intact on disk. Tags pin a snapshot by name, so retrieval systems and training runs can reproduce against an exact slice of history.

## Load with `datasets.load_dataset`

You can load Lance datasets via the standard HuggingFace `datasets` interface, suitable when your pipeline already speaks `Dataset` / `IterableDataset` or you want a quick streaming sample without installing anything Lance-specific.

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
import datasets

hf_ds = datasets.load_dataset("lance-format/oxford-pets-lance", split="train", streaming=True)
for row in hf_ds.take(3):
    print(row["label_name"], row["is_dog"])
```

## Load with LanceDB

LanceDB is the embedded retrieval library built on top of the Lance format ([docs](https://lancedb.com/docs)), and is the interface most users interact with. It wraps the dataset as a queryable table with search and filter builders, and is the entry point used by the Search, Curate, Evolve, Train, Versioning, and Materialize-a-subset sections below.

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
import lancedb

db = lancedb.connect("hf://datasets/lance-format/oxford-pets-lance/data")
tbl = db.open_table("train")
print(len(tbl))
```

## Load with Lance

`pylance` is the Python binding for the Lance format and works directly with the format's lower-level APIs. Reach for it when you want to inspect or operate on dataset internals — schema, scanner, fragments, and the list of pre-built indices.

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
import lance

ds = lance.dataset("hf://datasets/lance-format/oxford-pets-lance/data/train.lance")
print(ds.count_rows(), ds.schema.names)
print(ds.list_indices())
```

> **Tip — for production use, download locally first.** Streaming from the Hub works for exploration, but heavy random access and ANN search are far faster against a local copy:
>
> ```bash theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
> hf download lance-format/oxford-pets-lance --repo-type dataset --local-dir ./oxford-pets-lance
> ```
>
> Then point Lance or LanceDB at `./oxford-pets-lance/data`.

## Search

The bundled `IVF_PQ` index on `image_emb` makes approximate-nearest-neighbor search a single call. In production you would encode a query photo through the same OpenCLIP `ViT-B-32` model used at ingest and pass the resulting 512-d vector to `tbl.search(...)`. The example below uses the embedding stored in row 0 as a runnable stand-in so the snippet works without a model loaded; on a clean run the first hit is expected to be the seed image itself, which is a useful sanity check on the index.

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
import lancedb

db = lancedb.connect("hf://datasets/lance-format/oxford-pets-lance/data")
tbl = db.open_table("train")

seed = (
    tbl.search()
    .select(["image_emb", "label_name", "is_dog"])
    .limit(1)
    .to_list()[0]
)

hits = (
    tbl.search(seed["image_emb"])
    .metric("cosine")
    .select(["id", "label_name", "is_dog"])
    .limit(10)
    .to_list()
)
print(f"seed: {seed['label_name']} (is_dog={seed['is_dog']})")
for r in hits:
    print(f"  {r['id']:>5}  {r['label_name']:<22}  is_dog={r['is_dog']}")
```

Tune `metric`, `nprobes`, and `refine_factor` to trade recall against latency for your workload.

## Curate

A typical curation pass for a fine-grained pet classifier stacks the species predicate and a breed predicate inside a single filtered scan. With bitmap indices on both `label_name` and `is_dog`, the result comes back in milliseconds, and the bounded `.limit(200)` keeps it small enough to inspect or hand off to a training run.

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
import lancedb

db = lancedb.connect("hf://datasets/lance-format/oxford-pets-lance/data")
tbl = db.open_table("train")

candidates = (
    tbl.search()
    .where("is_dog = true AND label_name IN ('golden_retriever', 'beagle', 'pug')")
    .select(["id", "label_name", "is_dog", "path"])
    .limit(200)
    .to_list()
)
print(f"{len(candidates)} candidates; first: {candidates[0]['label_name']}")
```

The result is a plain list of dictionaries, ready to inspect, persist as a manifest of `id`s, or feed into the Evolve and Train workflows below. The `image` and `image_emb` columns are never read by this query, so the network traffic is dominated by the small label fields rather than JPEG bytes or vectors.

## Evolve

Lance stores each column independently, so a new column can be appended without rewriting the existing data. The lightest form is a SQL expression: derive the new column from columns that already exist, and Lance computes it once and persists it. The example below derives a `species` string from the `is_dog` boolean and adds a coarse breed-group flag for terriers, either of which can then be used directly in `where` clauses without recomputing the predicate on every query.

> **Note:** Mutations require a local copy of the dataset, since the Hub mount is read-only. See the Materialize-a-subset section at the end of this card for a streaming pattern that downloads only the rows and columns you need, or use `hf download` to pull the full split first.

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
import lancedb

db = lancedb.connect("./oxford-pets-lance/data")  # local copy required for writes
tbl = db.open_table("train")

tbl.add_columns({
    "species": "CASE WHEN is_dog THEN 'dog' ELSE 'cat' END",
    "is_terrier": "label_name LIKE '%terrier%'",
})
```

If the values you want to attach already live in another table (offline labels, classifier predictions, an integer class id), merge them in by joining on `id`:

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
import pyarrow as pa

class_ids = pa.table({
    "id": pa.array([0, 1, 2]),
    "label_int": pa.array([0, 0, 17]),
})
tbl.merge(class_ids, on="id")
```

The original columns and indices are untouched, so existing code that does not reference the new columns continues to work unchanged. New columns become visible to every reader as soon as the operation commits. For column values that require a Python computation (e.g., running a second embedding model over the JPEG bytes), Lance provides a batch-UDF API in the underlying library — see the [Lance data evolution docs](https://lance.org/guide/data_evolution/) for that pattern.

## Train

Projection lets a training loop read only the columns each step actually needs. LanceDB tables expose this through `Permutation.identity(tbl).select_columns([...])`, which plugs straight into the standard `torch.utils.data.DataLoader` so prefetch, shuffling, and batching behave as in any PyTorch pipeline. For a from-scratch breed classifier, project the JPEG bytes and the string breed label; for a linear probe on top of frozen CLIP features, swap the projection to the embedding column and skip JPEG decoding entirely.

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
import lancedb
from lancedb.permutation import Permutation
from torch.utils.data import DataLoader

db = lancedb.connect("hf://datasets/lance-format/oxford-pets-lance/data")
tbl = db.open_table("train")

train_ds = Permutation.identity(tbl).select_columns(["image", "label_name"])
loader = DataLoader(train_ds, batch_size=64, shuffle=True, num_workers=4)

for batch in loader:
    # batch carries only the projected columns; image_emb stays on disk.
    # decode the JPEG bytes, map label_name -> int via a class list, forward, cross-entropy...
    ...
```

Switching feature sets is a configuration change: passing `["image_emb", "label_name"]` to `select_columns(...)` on the next run reads only the cached 512-d vectors and the label, which is the right shape for a linear probe or a lightweight reranker. Projecting `["image", "is_dog"]` reduces the task to binary species classification on the same data.

## Versioning

Every mutation to a Lance dataset, whether it adds a column, merges labels, or builds an index, commits a new version. Previous versions remain intact on disk. You can list versions and inspect the history directly from the Hub copy; creating new tags requires a local copy since tags are writes.

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
import lancedb

db = lancedb.connect("hf://datasets/lance-format/oxford-pets-lance/data")
tbl = db.open_table("train")

print("Current version:", tbl.version)
print("History:", tbl.list_versions())
print("Tags:", tbl.tags.list())
```

Once you have a local copy, tag a version for reproducibility:

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
local_db = lancedb.connect("./oxford-pets-lance/data")
local_tbl = local_db.open_table("train")
local_tbl.tags.create("clip-vitb32-v1", local_tbl.version)
```

A tagged version can be opened by name, or any version reopened by its number, against either the Hub copy or a local one:

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
tbl_v1 = db.open_table("train", version="clip-vitb32-v1")
tbl_v5 = db.open_table("train", version=5)
```

Pinning supports two workflows. A retrieval system locked to `clip-vitb32-v1` keeps returning stable results while the dataset evolves in parallel; newly added columns or labels do not change what the tag resolves to. A training experiment pinned to the same tag can be rerun later against the exact same images and labels, so changes in metrics reflect model changes rather than data drift. Neither workflow needs shadow copies or external manifest tracking.

## Materialize a subset

Reads from the Hub are lazy, so exploratory queries only transfer the columns and row groups they touch. Mutating operations (Evolve, tag creation) need a writable backing store, and a training loop benefits from a local copy with fast random access. Both can be served by a subset of the dataset rather than the full split. The pattern is to stream a filtered query through `.to_batches()` into a new local table; only the projected columns and matching row groups cross the wire, and the bytes never fully materialize in Python memory.

```python theme={"theme":{"light":"vitesse-light","dark":"catppuccin-mocha"}}
import lancedb

remote_db = lancedb.connect("hf://datasets/lance-format/oxford-pets-lance/data")
remote_tbl = remote_db.open_table("train")

batches = (
    remote_tbl.search()
    .where("is_dog = true")
    .select(["id", "image", "label_name", "is_dog", "image_emb"])
    .to_batches()
)

local_db = lancedb.connect("./oxford-pets-dogs-subset")
local_db.create_table("train", batches)
```

The resulting `./oxford-pets-dogs-subset` is a first-class LanceDB database. Every snippet in the Evolve, Train, and Versioning sections above works against it by swapping `hf://datasets/lance-format/oxford-pets-lance/data` for `./oxford-pets-dogs-subset`.

## Source & license

Converted from [`pcuenq/oxford-pets`](https://huggingface.co/datasets/pcuenq/oxford-pets). Released under [CC BY-SA 4.0](https://creativecommons.org/licenses/by-sa/4.0/).

## Citation

```
@inproceedings{parkhi2012cats,
  title={Cats and Dogs},
  author={Parkhi, Omkar M. and Vedaldi, Andrea and Zisserman, Andrew and Jawahar, C. V.},
  booktitle={IEEE Conference on Computer Vision and Pattern Recognition (CVPR)},
  year={2012}
}
```