POC for Text mark

seaborn/_core/properties.py

@@ -298,6 +298,15 @@ class Alpha(IntervalProperty):
     # TODO validate / enforce that output is in [0, 1]
 
 
+class FontSize(IntervalProperty):
+    """Thickness of the edges on a patch mark, in points."""
+    @property
+    def default_range(self) -> tuple[float, float]:
+        """Min and max values used by default for semantic mapping."""
+        base = mpl.rcParams["font.size"]
+        return base * .5, base * 2
+
+
 # =================================================================================== #
 # Properties defined by arbitrary objects with inherently nominal scaling
 # =================================================================================== #
@@ -496,6 +505,26 @@ def _get_dash_pattern(style: str | DashPattern) -> DashPatternWithOffset:
         return offset, dashes
 
 
+class TextAlignment(ObjectProperty):
+    legend = False
+
+
+class HorizontalAlignment(TextAlignment):
+    legend = False
+
+    def _default_values(self, n: int) -> list:
+        vals = itertools.cycle(["left", "right"])
+        return [next(vals) for _ in range(n)]
+
+
+class VerticalAlignment(TextAlignment):
+    legend = False
+
+    def _default_values(self, n: int) -> list:
+        vals = itertools.cycle(["top", "bottom"])
+        return [next(vals) for _ in range(n)]
+
+
 # =================================================================================== #
 # Properties with  RGB(A) color values
 # =================================================================================== #
@@ -751,6 +780,10 @@ def mapping(x):
     "edgestyle": LineStyle,
     "edgecolor": Color,
     "edgealpha": Alpha,
+    "text": Property,
+    "halign": HorizontalAlignment,
+    "valign": VerticalAlignment,
+    "fontsize": FontSize,
     "xmin": Coordinate,
     "xmax": Coordinate,
     "ymin": Coordinate,

seaborn/_marks/text.py

@@ -0,0 +1,64 @@
+from __future__ import annotations
+from collections import defaultdict
+from dataclasses import dataclass
+from typing import Any
+
+import numpy as np
+import matplotlib as mpl
+from matplotlib.artist import Artist
+
+from seaborn._marks.base import (
+    Mark,
+    Mappable,
+    MappableFloat,
+    MappableString,
+    MappableColor,
+    resolve_properties,
+    document_properties,
+)
+from seaborn._core.scales import Scale
+
+
+@document_properties
+@dataclass
+class Text(Mark):
+    """
+    TODO
+    """
+
+    text: MappableString = Mappable("")
+    color: MappableColor = Mappable("k")
+    fontsize: MappableFloat = Mappable(rc="font.size")
+    halign: MappableString = Mappable("center")
+    valign: MappableString = Mappable("center_baseline")
+
+    def _plot(self, split_gen, scales, orient):
+
+        ax_data = defaultdict(list)
+
+        for keys, data, ax in split_gen():
+            vals = resolve_properties(self, keys, scales)
+
+            for row in data.to_dict("records"):
+                artist = mpl.text.Text(
+                    x=row["x"],
+                    y=row["y"],
+                    text=str(row["text"]),  # TODO format
+                    color=vals["color"],
+                    fontsize=vals["fontsize"],
+                    horizontalalignment=vals["halign"],
+                    verticalalignment=vals["valign"],
+                    **self.artist_kws,
+                )
+                ax.add_artist(artist)
+                ax_data[ax].append([row["x"], row["y"]])
+
+        for ax, ax_vals in ax_data.items():
+            ax.update_datalim(np.array(ax_vals))
+
+    def _legend_artist(
+        self, variables: list[str], value: Any, scales=dict[str, Scale],
+    ) -> Artist:
+
+        # TODO
+        return mpl.line.Line2D()

seaborn/objects.py

@@ -31,8 +31,9 @@
 from seaborn._marks.base import Mark  # noqa: F401
 from seaborn._marks.area import Area, Band  # noqa: F401
 from seaborn._marks.bar import Bar, Bars  # noqa: F401
-from seaborn._marks.line import Line, Lines, Path, Paths, Range  # noqa: F401
 from seaborn._marks.dot import Dot, Dots  # noqa: F401
+from seaborn._marks.line import Line, Lines, Path, Paths, Range  # noqa: F401
+from seaborn._marks.text import Text  # noqa: F401
 
 from seaborn._stats.base import Stat  # noqa: F401
 from seaborn._stats.aggregation import Agg, Est  # noqa: F401