feat(python): align to_pandas pandas kwargs (#3397)

## Feature

This PR aligns LanceDB Python `to_pandas()` APIs with Lance pandas
conversion capabilities while keeping LanceDB query-specific semantics
intact.

- Adds `blob_mode` and pandas `**kwargs` support to local table
`to_pandas()`.
- Delegates local `LanceTable.to_pandas()` to Lance dataset
`to_pandas(blob_mode=..., **kwargs)`.
- Keeps remote table `to_pandas()` unsupported with
`NotImplementedError`.
- Allows sync and async query `to_pandas()` to forward pandas kwargs
after LanceDB `flatten` and `timeout` handling.

Why we need this feature:

Users can access Lance blob-aware pandas conversion from LanceDB local
tables and can pass PyArrow pandas conversion options through
table/query APIs without losing existing `flatten` or `timeout`
behavior.

How it works:

The table API exposes a `BlobMode` literal type for `lazy`, `bytes`, and
`descriptions`. Local tables call through to the backing Lance dataset.
Query APIs do not add `blob_mode`; they materialize Arrow results, apply
LanceDB flattening when requested, and then call `to_pandas(**kwargs)`.

## Validation

- `uv run --frozen --extra tests pytest
python/tests/test_table.py::test_table_to_pandas_default_matches_arrow
python/tests/test_table.py::test_table_to_pandas_blob_bytes
python/tests/test_table.py::test_table_to_pandas_kwargs
python/tests/test_query.py::test_query_to_pandas_kwargs
python/tests/test_query.py::test_query_timeout
python/tests/test_remote_db.py::test_table_to_pandas_not_supported`
- `uv run --frozen --extra dev ruff check python/lancedb/table.py
python/lancedb/query.py python/lancedb/remote/table.py
python/tests/test_table.py python/tests/test_query.py
python/tests/test_remote_db.py`
- `uv run --frozen --extra tests pytest python/tests/test_table.py
python/tests/test_query.py python/tests/test_remote_db.py`

Note: `python/uv.lock` was intentionally not committed in this branch.
This commit is contained in:
Yang Cen
2026-05-19 20:05:51 +08:00
committed by GitHub
parent 53c2164b84
commit 5d1c28922a
7 changed files with 186 additions and 12 deletions

View File

@@ -47,6 +47,85 @@ def test_basic(mem_db: DBConnection):
assert table.to_arrow() == expected_data
def test_table_to_pandas_default_matches_arrow(tmp_db: DBConnection):
pd = pytest.importorskip("pandas")
data = pa.table({"id": [1, 2], "text": ["one", "two"]})
table = tmp_db.create_table("test_to_pandas_old_call", data=data)
expected = data.to_pandas()
pd.testing.assert_frame_equal(table.to_pandas(), expected)
def test_table_to_pandas_blob_bytes(tmp_db: DBConnection):
pytest.importorskip("lance")
data = pa.table(
{
"id": pa.array([1, 2], pa.int64()),
"blob": pa.array([b"hello", b"world"], pa.large_binary()),
},
schema=pa.schema(
[
pa.field("id", pa.int64()),
pa.field(
"blob", pa.large_binary(), metadata={"lance-encoding:blob": "true"}
),
]
),
)
table = tmp_db.create_table("test_to_pandas_blob_bytes", data=data)
df = table.to_pandas(blob_mode="bytes")
assert df["blob"].tolist() == [b"hello", b"world"]
def test_table_to_pandas_kwargs(tmp_db: DBConnection):
pd = pytest.importorskip("pandas")
data = pa.table({"id": pa.array([1, 2], pa.int64())})
table = tmp_db.create_table("test_to_pandas_kwargs", data=data)
df = table.to_pandas(types_mapper=pd.ArrowDtype)
assert str(df["id"].dtype) == "int64[pyarrow]"
@pytest.mark.asyncio
async def test_async_table_to_pandas_blob_bytes(tmp_db_async: AsyncConnection):
pytest.importorskip("lance")
data = pa.table(
{
"id": pa.array([1, 2], pa.int64()),
"blob": pa.array([b"hello", b"world"], pa.large_binary()),
},
schema=pa.schema(
[
pa.field("id", pa.int64()),
pa.field(
"blob", pa.large_binary(), metadata={"lance-encoding:blob": "true"}
),
]
),
)
table = await tmp_db_async.create_table(
"test_async_to_pandas_blob_bytes", data=data
)
df = await table.to_pandas(blob_mode="bytes")
assert df["blob"].tolist() == [b"hello", b"world"]
@pytest.mark.asyncio
async def test_async_table_to_pandas_kwargs(tmp_db_async: AsyncConnection):
pd = pytest.importorskip("pandas")
data = pa.table({"id": pa.array([1, 2], pa.int64())})
table = await tmp_db_async.create_table("test_async_to_pandas_kwargs", data=data)
df = await table.to_pandas(types_mapper=pd.ArrowDtype)
assert str(df["id"].dtype) == "int64[pyarrow]"
def test_create_table_infers_large_int_vectors(mem_db: DBConnection):
data = [{"vector": [0, 300]}]