feat: add is_into_dataframe (#1288)

* add is_into_dataframe

* fix pyarrow table construct

* typo series-> dataframe

docs/api-reference/dependencies.md

@@ -15,6 +15,7 @@
         - is_cudf_series
         - is_dask_dataframe
         - is_ibis_table
+        - is_into_dataframe
         - is_into_series
         - is_modin_dataframe
         - is_modin_index

narwhals/dependencies.py

@@ -251,6 +251,44 @@ def is_into_series(native_series: IntoSeries) -> bool:
     )
 
 
+def is_into_dataframe(native_dataframe: Any) -> bool:
+    """
+    Check whether `native_dataframe` can be converted to a Narwhals DataFrame.
+
+    Arguments:
+        native_dataframe: The object to check.
+
+    Returns:
+        `True` if `native_dataframe` can be converted to a Narwhals DataFrame, `False` otherwise.
+
+    Examples:
+        >>> import pandas as pd
+        >>> import polars as pl
+        >>> import numpy as np
+        >>> from narwhals.dependencies import is_into_dataframe
+
+        >>> df_pd = pd.DataFrame({"a": [1, 2, 3], "b": [4, 5, 6]})
+        >>> df_pl = pl.DataFrame({"a": [1, 2, 3], "b": [4, 5, 6]})
+        >>> np_arr = np.array([[1, 4], [2, 5], [3, 6]])
+
+        >>> is_into_dataframe(df_pd)
+        True
+        >>> is_into_dataframe(df_pl)
+        True
+        >>> is_into_dataframe(np_arr)
+        False
+    """
+    from narwhals.dataframe import DataFrame
+
+    return (
+        isinstance(native_dataframe, DataFrame)
+        or hasattr(native_dataframe, "__narwhals_dataframe__")
+        or is_polars_dataframe(native_dataframe)
+        or is_pyarrow_table(native_dataframe)
+        or is_pandas_like_dataframe(native_dataframe)
+    )
+
+
 __all__ = [
     "get_polars",
     "get_pandas",
@@ -275,5 +313,6 @@ def is_into_series(native_series: IntoSeries) -> bool:
     "is_dask_dataframe",
     "is_pandas_like_dataframe",
     "is_pandas_like_series",
+    "is_into_dataframe",
     "is_into_series",
 ]

tests/dependencies/is_into_dataframe_test.py

@@ -0,0 +1,37 @@
+from __future__ import annotations
+
+from typing import TYPE_CHECKING
+from typing import Any
+
+import numpy as np
+import pandas as pd
+import polars as pl
+import pyarrow as pa
+
+import narwhals as nw
+from narwhals.dependencies import is_into_dataframe
+
+if TYPE_CHECKING:
+    from typing_extensions import Self
+
+
+class DictDataFrame:
+    def __init__(self, data: dict[str, list[Any]]) -> None:
+        self._data = data
+
+    def __len__(self) -> int:  # pragma: no cover
+        return len(next(iter(self._data.values())))
+
+    def __narwhals_dataframe__(self) -> Self:  # pragma: no cover
+        return self
+
+
+def test_is_into_dataframe() -> None:
+    data = {"a": [1, 2, 3], "b": [4, 5, 6]}
+    assert is_into_dataframe(pa.table(data))
+    assert is_into_dataframe(pl.DataFrame(data))
+    assert is_into_dataframe(pd.DataFrame(data))
+    assert is_into_dataframe(nw.from_native(pd.DataFrame(data)))
+    assert is_into_dataframe(DictDataFrame(data))
+    assert not is_into_dataframe(np.array([[1, 4], [2, 5], [3, 6]]))
+    assert not is_into_dataframe(data)