Add datetime coordinate formatting for cursor and stats tools

- Cursor tools (VCursor, HCursor, XCursor) now display datetime coordinates
- CurveStatsTool shows datetime-formatted X values
- Refactored datetime formatting to eliminate code duplication
- Added BasePlot.format_coordinate_value() for consistent formatting

Author: PierreRaybaut

CHANGELOG.md

@@ -43,6 +43,13 @@
   * Configurable label rotation and spacing for optimal display
   * Example: `plot.set_axis_datetime("bottom", format="%H:%M:%S")` for time-only display
   * Example: `plot.set_axis_limits_from_datetime("bottom", dt1, dt2)` to zoom to a specific time range
+  * Added `"datetime"` as a valid scale type (alongside `"lin"` and `"log"`) for axis configuration
+  * Added datetime coordinate formatting support throughout PlotPy:
+    * Cursor tools (`VCursorTool`, `HCursorTool`, `XCursorTool`) now display datetime-formatted X/Y coordinates
+    * `CurveStatsTool` now displays datetime-formatted X coordinates for statistical computations
+    * Marker labels automatically format coordinates as datetime when axis uses datetime scale
+    * Coordinate display in the plot canvas now shows datetime format when appropriate
+    * Refactored `ObjectInfo` base class to provide shared datetime formatting methods for code reuse
 
 🧹 API cleanup: removed deprecated update methods (use `update_item` instead)
 

plotpy/items/curve/base.py

@@ -26,6 +26,7 @@
     import guidata.io
 
     from plotpy.interfaces import IItemType
+    from plotpy.plot import BasePlot
     from plotpy.styles.base import ItemParameters
 
 
@@ -503,7 +504,16 @@ def get_coordinates_label(self, x: float, y: float) -> str:
             str: Coordinates label
         """
         title = self.title().text()
-        return f"{title}:<br>x = {x:g}<br>y = {y:g}"
+
+        # Use the plot's consolidated coordinate formatting method
+        plot: BasePlot = self.plot()
+        if plot is not None:
+            # Format using the plot's consolidated coordinate formatting method
+            return plot.format_coordinate_values(
+                x, y, self.xAxis(), self.yAxis(), title
+            )
+        else:
+            return f"{title}:<br>x = {x:g}<br>y = {y:g}"
 
     def get_closest_x(self, xc: float) -> tuple[float, float]:
         """

plotpy/items/label.py

@@ -13,6 +13,7 @@
 
 from __future__ import annotations
 
+import re
 from typing import TYPE_CHECKING, Any
 
 import numpy as np
@@ -26,6 +27,7 @@
 from plotpy.coords import canvas_to_axes
 from plotpy.interfaces import IBasePlotItem, ISerializableType, IShapeItemType
 from plotpy.items.curve.base import CurveItem
+from plotpy.items.shape.range import XRangeSelection
 from plotpy.styles.label import LabelParam
 
 if TYPE_CHECKING:
@@ -38,7 +40,7 @@
     from qtpy.QtGui import QBrush, QPainter, QPen, QTextDocument
 
     from plotpy.interfaces import IItemType
-    from plotpy.items import ImageItem, RectangleShape, XRangeSelection, YRangeSelection
+    from plotpy.items import ImageItem, RectangleShape, YRangeSelection
     from plotpy.styles.base import ItemParameters
 
 ANCHORS = {
@@ -910,6 +912,85 @@ def get_text(self) -> str:
         """Return the text to be displayed"""
         return ""
 
+    @staticmethod
+    def _replace_format_specifiers(label: str, datetime_positions: list[int]) -> str:
+        """Replace numeric format specifiers with %s for datetime positions
+
+        Args:
+            label: The label format string
+            datetime_positions: List of positions that should use %s
+
+        Returns:
+            Modified label string
+        """
+        # Find all format specifiers
+        pattern = r"%[+-]?(?:\d+)?(?:\.\d+)?[hlL]?[diouxXeEfFgGcrs%]"
+        matches = list(re.finditer(pattern, label))
+
+        # Replace numeric formats with %s for datetime positions
+        result = label
+        offset = 0
+        spec_index = 0
+
+        for match in matches:
+            if match.group() == "%%":  # Skip escaped %
+                continue
+
+            if spec_index in datetime_positions:
+                # Replace this format specifier with %s
+                old_spec = match.group()
+                new_spec = "%s"
+                start = match.start() + offset
+                end = match.end() + offset
+                result = result[:start] + new_spec + result[end:]
+                offset += len(new_spec) - len(old_spec)
+
+            spec_index += 1
+
+        return result
+
+    @staticmethod
+    def _format_values_for_datetime_axis(
+        plot, axis_id: int, label: str, result: tuple | list, value_checker: Callable
+    ) -> tuple[str, tuple]:
+        """Format values as datetime strings if they match the value_checker criterion
+
+        Args:
+            plot: The plot object
+            axis_id: The axis ID to check for datetime scale
+            label: The label format string
+            result: The result tuple/list from the function
+            value_checker: Function that takes (value, index) and returns True if the
+             value should be formatted as datetime
+
+        Returns:
+            Tuple of (adjusted_label, formatted_result)
+        """
+        # Check if axis is datetime
+        if plot.get_axis_scale(axis_id) != "datetime":
+            return label, result
+
+        # Convert result to list for modification
+        if not isinstance(result, (list, tuple)):
+            result = [result]
+        else:
+            result = list(result)
+
+        # Find positions that need datetime formatting
+        datetime_positions = []
+        for i, val in enumerate(result):
+            if isinstance(val, (int, float, np.number)) and not np.isnan(val):
+                if value_checker(val, i):
+                    datetime_positions.append(i)
+                    # Format as datetime string
+                    result[i] = plot.format_coordinate_value(val, axis_id)
+
+        # Replace format specifiers for datetime positions in the label
+        if datetime_positions:
+            label = ObjectInfo._replace_format_specifiers(label, datetime_positions)
+
+        return label, tuple(result)
+
 
 class RangeInfo(ObjectInfo):
     """ObjectInfo handling `XRangeSelection` or `YRangeSelection`
@@ -949,7 +1030,29 @@ def get_text(self) -> str:
         v0, v1 = self.range.get_range()
         v = 0.5 * (v0 + v1)
         dv = 0.5 * (v1 - v0)
-        return self.label % self.func(v, dv)
+
+        # Get result from function
+        result = self.func(v, dv)
+
+        # Check if we need to format as datetime
+        plot = self.range.plot()
+        if plot is not None:
+            # Determine which axis this range is on
+            if isinstance(self.range, XRangeSelection):
+                axis_id = self.range.xAxis()
+            else:
+                axis_id = self.range.yAxis()
+
+            # Value checker: returns True if value matches v or dv (likely datetime)
+            def is_range_value(val, _idx):
+                return abs(val - v) < 1e-10 or abs(abs(val) - abs(dv)) < 1e-10
+
+            label, result = self._format_values_for_datetime_axis(
+                plot, axis_id, self.label, result, is_range_value
+            )
+            return label % result
+
+        return self.label % result
 
 
 class XRangeComputation(ObjectInfo):
@@ -1008,7 +1111,34 @@ def get_text(self) -> str:
                 vectors.append(np.array([np.nan]))
             else:
                 vectors.append(vector[i0:i1])
-        return self.label % self.func(*vectors)
+
+        # Get result from function
+        result = self.func(*vectors)
+
+        # Format values considering datetime axis
+        plot = self.curve.plot()
+        if plot is not None:
+            # Check if x-axis is datetime
+            x_axis = self.curve.xAxis()
+
+            # Compute x-statistics to identify x-coordinates in result
+            x_vector = vectors[0]
+            x_stats = set()
+            if x_vector is not None and len(x_vector) > 0:
+                x_stats = {x_vector.min(), x_vector.max(), x_vector.mean()}
+
+            # Value checker: returns True if value matches an x-statistic
+            def is_x_coordinate(val, _idx):
+                return any(
+                    abs(val - stat) < 1e-10 for stat in x_stats if not np.isnan(stat)
+                )
+
+            label, result = self._format_values_for_datetime_axis(
+                plot, x_axis, self.label, result, is_x_coordinate
+            )
+            return label % result
+
+        return self.label % result
 
 
 RangeComputation = XRangeComputation  # For backward compatibility

plotpy/items/shape/marker.py

@@ -26,6 +26,7 @@
     from qtpy.QtGui import QPainter
 
     from plotpy.interfaces import IItemType
+    from plotpy.plot import BasePlot
     from plotpy.styles.base import ItemParameters
 
 
@@ -510,16 +511,41 @@ def invalidate_plot(self) -> None:
     def update_label(self) -> None:
         """Update label"""
         x, y = self.xValue(), self.yValue()
+        plot: BasePlot = self.plot()
         if self.label_cb:
             label = self.label_cb(x, y)
             if label is None:
                 return
         elif self.is_vertical():
-            label = f"x = {x:g}"
+            # Format x-coordinate considering datetime axis
+            if plot is not None and plot.get_axis_scale(self.xAxis()) == "datetime":
+                x_formatted = plot.format_coordinate_value(x, self.xAxis())
+                label = f"x = {x_formatted}"
+            else:
+                label = f"x = {x:g}"
         elif self.is_horizontal():
-            label = f"y = {y:g}"
+            # Format y-coordinate considering datetime axis
+            if plot is not None and plot.get_axis_scale(self.yAxis()) == "datetime":
+                y_formatted = plot.format_coordinate_value(y, self.yAxis())
+                label = f"y = {y_formatted}"
+            else:
+                label = f"y = {y:g}"
         else:
-            label = f"x = {x:g}<br>y = {y:g}"
+            # Format both coordinates considering datetime axes
+            if plot is not None:
+                x_formatted = x
+                y_formatted = y
+                if plot.get_axis_scale(self.xAxis()) == "datetime":
+                    x_formatted = plot.format_coordinate_value(x, self.xAxis())
+                else:
+                    x_formatted = f"{x:g}"
+                if plot.get_axis_scale(self.yAxis()) == "datetime":
+                    y_formatted = plot.format_coordinate_value(y, self.yAxis())
+                else:
+                    y_formatted = f"{y:g}"
+                label = f"x = {x_formatted}<br>y = {y_formatted}"
+            else:
+                label = f"x = {x:g}<br>y = {y:g}"
         text = self.label()
         text.setText(label)
         self.setLabel(text)

plotpy/locale/fr/LC_MESSAGES/plotpy.po

@@ -6,7 +6,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: plotpy 2.7.4\n"
 "Report-Msgid-Bugs-To: p.raybaut@codra.fr\n"
-"POT-Creation-Date: 2025-07-27 15:03+0200\n"
+"POT-Creation-Date: 2025-10-08 11:19+0200\n"
 "PO-Revision-Date: 2025-06-02 11:14+0200\n"
 "Last-Translator: Christophe Debonnel <c.debonnel@codra.fr>\n"
 "Language: fr\n"
@@ -356,15 +356,18 @@ msgstr "Police du titre"
 msgid "Values font"
 msgstr "Police des valeurs"
 
+msgid "Scale"
+msgstr "Échelle"
+
 msgid "linear"
 msgstr "linéaire"
 
+msgid "date/time"
+msgstr "date/heure"
+
 msgid "logarithmic"
 msgstr "logarithmique"
 
-msgid "Scale"
-msgstr "Échelle"
-
 msgid "Lower axis limit"
 msgstr "Borne inférieure de l'axe"