Fix Altair chart concatenation and stubs

Author: r3kste

docs/source/how_to/how_to_change_plotting_backend.ipynb

@@ -66,7 +66,7 @@
     "The returned figure object is an [`altair.Chart`](https://altair-viz.github.io/user_guide/generated/toplevel/altair.Chart.html).\n",
     "\n",
     "```{note}\n",
-    "In case of grid plots (such as `convergence_plot` or `slice_plot`), the returned object is an [`altair.VConcatChart`](https://altair-viz.github.io/user_guide/generated/toplevel/altair.VConcatChart.html).\n",
+    "In case of grid plots (such as `convergence_plot` or `slice_plot`), the returned object is either an [`altair.HConcatChart`](https://altair-viz.github.io/user_guide/generated/toplevel/altair.HConcatChart.html) if there is only one row, or an [`altair.VConcatChart`](https://altair-viz.github.io/user_guide/generated/toplevel/altair.VConcatChart.html) otherwise.\n",
     "```\n",
     "\n",
     ":::\n",
@@ -207,7 +207,7 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "optimagic",
    "language": "python",
    "name": "python3"
   },
@@ -221,7 +221,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.10.18"
+   "version": "3.10.17"
   }
  },
  "nbformat": 4,

src/optimagic/optimization/history.py

@@ -207,7 +207,7 @@ def params_data(
         """
         wide = pd.DataFrame(self.flat_params, columns=self.flat_param_names)
         wide["task"] = _task_to_categorical(self.task)
-        wide["fun"] = self.fun
+        wide["fun"] = self.fun  # type: ignore[assignment]
 
         # If requested, we collapse the batches and only keep the parameters that led to
         # the minimal (or maximal) function value in each batch.

src/optimagic/visualization/backends.py

@@ -729,15 +729,16 @@ def _grid_line_plot_altair(
     plot_title: str | None,
     marker_list: list[MarkerData] | None,
     make_subplot_kwargs: dict[str, Any] | None = None,
-) -> "alt.VConcatChart":
+) -> "alt.Chart | alt.HConcatChart | alt.VConcatChart":
     """Create a grid of line plots using Altair.
 
     Args:
         ...: All other argument descriptions can be found in the docstring of the
             `grid_line_plot` function.
 
     Returns:
-        An Altair VConcatChart object.
+        An Altair Chart if the grid contains only one subplot, an Altair HConcatChart
+            if 'n_rows' is 1, otherwise an Altair VConcatChart.
 
     """
     import altair as alt
@@ -774,10 +775,16 @@ def _grid_line_plot_altair(
         charts.append(chart_row)
 
     row_selections = [
-        alt.selection_interval(bind="scales", encodings=["y"]) for _ in range(n_rows)
+        alt.selection_interval(
+            bind="scales", encodings=["y"], name=f"share_y_row{row_idx}"
+        )
+        for row_idx in range(n_rows)
     ]
     col_selections = [
-        alt.selection_interval(bind="scales", encodings=["x"]) for _ in range(n_cols)
+        alt.selection_interval(
+            bind="scales", encodings=["x"], name=f"share_x_col{col_idx}"
+        )
+        for col_idx in range(n_cols)
     ]
 
     for row_idx, row in enumerate(charts):
@@ -790,13 +797,25 @@ def _grid_line_plot_altair(
                 params.append(row_selections[row_idx])
             else:
                 # Use independent y-axes for each subplot
-                params.append(alt.selection_interval(bind="scales", encodings=["y"]))
+                params.append(
+                    alt.selection_interval(
+                        bind="scales",
+                        encodings=["x", "y"],
+                        name=f"ind_y_row{row_idx}_col{col_idx}",
+                    )
+                )
             if share_x:
                 # Share x-axis for all subplots in the same column
                 params.append(col_selections[col_idx])
             else:
                 # Use independent x-axes for each subplot
-                params.append(alt.selection_interval(bind="scales", encodings=["x"]))
+                params.append(
+                    alt.selection_interval(
+                        bind="scales",
+                        encodings=["x", "y"],
+                        name=f"ind_x_row{row_idx}_col{col_idx}",
+                    )
+                )
             chart = chart.add_params(*params)
 
             if share_y and col_idx > 0:
@@ -808,7 +827,20 @@ def _grid_line_plot_altair(
 
             charts[row_idx][col_idx] = chart
 
-    grid_chart = alt.vconcat(*[alt.hconcat(*row) for row in charts])
+    row_charts = []
+    for row in charts:
+        row_chart: alt.Chart | alt.HConcatChart
+        if len(row) == 1:
+            row_chart = row[0]
+        else:
+            row_chart = alt.hconcat(*row)
+        row_charts.append(row_chart)
+
+    grid_chart: alt.Chart | alt.HConcatChart | alt.VConcatChart
+    if len(row_charts) == 1:
+        grid_chart = row_charts[0]
+    else:
+        grid_chart = alt.vconcat(*row_charts)
 
     if plot_title is not None:
         grid_chart = grid_chart.properties(title=plot_title)

src/optimagic/visualization/slice_plot.py

@@ -292,7 +292,7 @@ def _get_plot_data(
         metadata.append(meta)
 
     plot_data = pd.DataFrame(metadata)
-    plot_data["Function Value"] = func_values
+    plot_data["Function Value"] = func_values  # type: ignore[assignment]
 
     return plot_data, internal_params