expanding plotting backends.

py-polars/polars/dataframe/frame.py

@@ -64,7 +64,7 @@
 from polars._utils.wrap import wrap_expr, wrap_ldf, wrap_s
 from polars.dataframe._html import NotebookFormatter
 from polars.dataframe.group_by import DynamicGroupBy, GroupBy, RollingGroupBy
-from polars.dataframe.plotting import DataFramePlot
+from polars.dataframe.plotting.plotting import DataFramePlot
 from polars.datatypes import (
     N_INFER_DEFAULT,
     Boolean,
@@ -611,7 +611,7 @@ def _replace(self, column: str, new_column: Series) -> DataFrame:
 
     @property
     @unstable()
-    def plot(self) -> DataFramePlot:
+    def plot(self, backend: str | None = None) -> DataFramePlot:
         """
         Create a plot namespace.
 
@@ -704,7 +704,7 @@ def plot(self) -> DataFramePlot:
         if not _ALTAIR_AVAILABLE or parse_version(altair.__version__) < (5, 4, 0):
             msg = "altair>=5.4.0 is required for `.plot`"
             raise ModuleUpgradeRequiredError(msg)
-        return DataFramePlot(self)
+        return DataFramePlot(self, backend)
 
     @property
     @unstable()

py-polars/polars/dataframe/plotting.py → py-polars/polars/dataframe/plotting/plotting.py

@@ -1,8 +1,8 @@
 from __future__ import annotations
 
 import inspect
-from typing import TYPE_CHECKING, Callable, Union
-
+from typing import TYPE_CHECKING, Any, Callable, Union
+import os
 from polars.dependencies import altair as alt
 
 if TYPE_CHECKING:
@@ -34,6 +34,38 @@
 class DataFramePlot:
     """DataFrame.plot namespace."""
 
+    def __init__(self, df: DataFrame, backend: str | None = None) -> None:
+        self._df = df
+        # TODO: add config for backend
+        if backend is None and "POLARS_PLOTTING_BACKEND" in os.environ:
+            backend = os.environ["POLARS_PLOTTING_BACKEND"]
+        elif backend is None:
+            backend = (
+                "altair"  # TODO: change from default to detecting installed library
+            )
+
+        if backend == "altair":
+            self._backend = AltairPlot(df)
+
+    def bar(
+        self,
+        x: X | None = None,
+        y: Y | None = None,
+        color: Color | None = None,
+        /,
+        **kwargs: Any,
+    ) -> Any:
+        return self._backend.bar(x, y, color, **kwargs)
+
+    def alt(self) -> AltairPlot:
+        # going through the extra class makes it so users can get the right static
+        # typed outputs or
+        return AltairPlot(self._df)
+
+
+class AltairPlot:
+    """DataFrame.plot namespace for altair."""
+
     def __init__(self, df: DataFrame) -> None:
         self._chart = alt.Chart(df)
 

py-polars/polars/series/plotting.py

@@ -10,7 +10,7 @@
 
     from altair.typing import EncodeKwds
 
-    from polars.dataframe.plotting import Encodings
+    from polars.dataframe.plotting.plotting import Encodings
 
     if sys.version_info >= (3, 11):
         from typing import Unpack