feat(python): add tooltip by default to charts

py-polars/polars/dataframe/plotting.py

@@ -7,12 +7,24 @@
 
     import altair as alt
     from altair.typing import (
-        ChannelColor,
-        ChannelOrder,
-        ChannelSize,
-        ChannelTooltip,
-        ChannelX,
-        ChannelY,
+        ChannelColor as Color,
+    )
+    from altair.typing import (
+        ChannelOrder as Order,
+    )
+    from altair.typing import (
+        ChannelSize as Size,
+    )
+    from altair.typing import (
+        ChannelTooltip as Tooltip,
+    )
+    from altair.typing import (
+        ChannelX as X,
+    )
+    from altair.typing import (
+        ChannelY as Y,
+    )
+    from altair.typing import (
         EncodeKwds,
     )
 
@@ -29,12 +41,15 @@
 
     Encodings: TypeAlias = Dict[
         str,
-        Union[
-            ChannelX, ChannelY, ChannelColor, ChannelOrder, ChannelSize, ChannelTooltip
-        ],
+        Union[X, Y, Color, Order, Size, Tooltip],
     ]
 
 
+def _add_tooltip(chart: alt.Chart) -> alt.Chart:
+    chart.mark = {"type": chart.mark, "tooltip": True}
+    return chart
+
+
 class DataFramePlot:
     """DataFrame.plot namespace."""
 
@@ -45,10 +60,10 @@ def __init__(self, df: DataFrame) -> None:
 
     def bar(
         self,
-        x: ChannelX | None = None,
-        y: ChannelY | None = None,
-        color: ChannelColor | None = None,
-        tooltip: ChannelTooltip | None = None,
+        x: X | None = None,
+        y: Y | None = None,
+        color: Color | None = None,
+        tooltip: Tooltip | None = None,
         /,
         **kwargs: Unpack[EncodeKwds],
     ) -> alt.Chart:
@@ -104,15 +119,17 @@ def bar(
             encodings["color"] = color
         if tooltip is not None:
             encodings["tooltip"] = tooltip
-        return self._chart.mark_bar().encode(**encodings, **kwargs).interactive()
+        return _add_tooltip(
+            self._chart.mark_bar().encode(**encodings, **kwargs).interactive()
+        )
 
     def line(
         self,
-        x: ChannelX | None = None,
-        y: ChannelY | None = None,
-        color: ChannelColor | None = None,
-        order: ChannelOrder | None = None,
-        tooltip: ChannelTooltip | None = None,
+        x: X | None = None,
+        y: Y | None = None,
+        color: Color | None = None,
+        order: Order | None = None,
+        tooltip: Tooltip | None = None,
         /,
         **kwargs: Unpack[EncodeKwds],
     ) -> alt.Chart:
@@ -170,15 +187,17 @@ def line(
             encodings["order"] = order
         if tooltip is not None:
             encodings["tooltip"] = tooltip
-        return self._chart.mark_line().encode(**encodings, **kwargs).interactive()
+        return _add_tooltip(
+            self._chart.mark_line().encode(**encodings, **kwargs).interactive()
+        )
 
     def point(
         self,
-        x: ChannelX | None = None,
-        y: ChannelY | None = None,
-        color: ChannelColor | None = None,
-        size: ChannelSize | None = None,
-        tooltip: ChannelTooltip | None = None,
+        x: X | None = None,
+        y: Y | None = None,
+        color: Color | None = None,
+        size: Size | None = None,
+        tooltip: Tooltip | None = None,
         /,
         **kwargs: Unpack[EncodeKwds],
     ) -> alt.Chart:
@@ -236,7 +255,7 @@ def point(
             encodings["size"] = size
         if tooltip is not None:
             encodings["tooltip"] = tooltip
-        return (
+        return _add_tooltip(
             self._chart.mark_point()
             .encode(
                 **encodings,
@@ -253,4 +272,4 @@ def __getattr__(self, attr: str) -> Callable[..., alt.Chart]:
         if method is None:
             msg = "Altair has no method 'mark_{attr}'"
             raise AttributeError(msg)
-        return lambda **kwargs: method().encode(**kwargs).interactive()
+        return lambda **kwargs: _add_tooltip(method().encode(**kwargs).interactive())

py-polars/polars/series/plotting.py

@@ -2,6 +2,7 @@
 
 from typing import TYPE_CHECKING, Callable
 
+from polars.dataframe.plotting import add_tooltip
 from polars.dependencies import altair as alt
 
 if TYPE_CHECKING:
@@ -62,7 +63,7 @@ def hist(
         if self._series_name == "count()":
             msg = "Cannot use `plot.hist` when Series name is `'count()'`"
             raise ValueError(msg)
-        return (
+        return add_tooltip(
             alt.Chart(self._df)
             .mark_bar()
             .encode(x=alt.X(f"{self._series_name}:Q", bin=True), y="count()", **kwargs)  # type: ignore[misc]
@@ -104,7 +105,7 @@ def kde(
         if self._series_name == "density":
             msg = "Cannot use `plot.kde` when Series name is `'density'`"
             raise ValueError(msg)
-        return (
+        return add_tooltip(
             alt.Chart(self._df)
             .transform_density(self._series_name, as_=[self._series_name, "density"])
             .mark_area()
@@ -147,7 +148,7 @@ def line(
         if self._series_name == "index":
             msg = "Cannot call `plot.line` when Series name is 'index'"
             raise ValueError(msg)
-        return (
+        return add_tooltip(
             alt.Chart(self._df.with_row_index())
             .mark_line()
             .encode(x="index", y=self._series_name, **kwargs)  # type: ignore[misc]
@@ -165,8 +166,6 @@ def __getattr__(self, attr: str) -> Callable[..., alt.Chart]:
         if method is None:
             msg = "Altair has no method 'mark_{attr}'"
             raise AttributeError(msg)
-        return (
-            lambda **kwargs: method()
-            .encode(x="index", y=self._series_name, **kwargs)
-            .interactive()
+        return lambda **kwargs: add_tooltip(
+            method().encode(x="index", y=self._series_name, **kwargs).interactive()
         )