feat: add picker selector

src/biaplotter/_tests/test_selectors.py

@@ -3,11 +3,39 @@
 import pytest
 
 from biaplotter.plotter import CanvasWidget
-from biaplotter.selectors import (BaseEllipseSelector, BaseLassoSelector,
-                                  BaseRectangleSelector,
-                                  InteractiveEllipseSelector,
-                                  InteractiveLassoSelector,
-                                  InteractiveRectangleSelector)
+from biaplotter.selectors import (
+    BaseEllipseSelector, BaseLassoSelector, BaseRectangleSelector,
+    InteractiveEllipseSelector, InteractiveLassoSelector, InteractiveRectangleSelector,
+    InteractiveClickSelector, BaseClickSelector
+)
+
+# --- Parametrized tests for BaseClickSelector threshold functionality ---
+@pytest.mark.parametrize(
+    "data, click, threshold, expected_indices",
+    [
+        # Click near [1, 1], within threshold
+        (np.array([[0, 0], [1, 1], [2, 2]]), (1.025, 1.025), 0.2, [1]),
+        # Click far from all points, outside threshold
+        (np.array([[0, 0], [1, 1], [2, 2]]), (10, 10), 0.5, []),
+        # Click exactly on [2, 2], within threshold
+        (np.array([[0, 0], [1, 1], [2, 2]]), (2, 2), 0.1, [2]),
+        # Click between [0,0] and [1,1], closer to [0,0]
+        (np.array([[0, 0], [1, 1], [2, 2]]), (0.1, 0.1), 0.5, [0]),
+        # Click between [0,0] and [1,1], but threshold too small
+        (np.array([[0, 0], [1, 1], [2, 2]]), (0.1, 0.1), 0.05, []),
+    ]
+)
+def test_base_click_selector_threshold(data, click, threshold, expected_indices):
+    fig, ax = plt.subplots()
+    ax.scatter(data[:, 0], data[:, 1])
+    selector = BaseClickSelector(ax)
+    selector.data = data
+    event = type('Event', (), {'xdata': click[0], 'ydata': click[1]})()
+    idx = selector.on_select(event, threshold=threshold)
+    if len(expected_indices) == 0:
+        assert len(idx) == 0, f"Expected empty array, got {idx}"
+    else:
+        assert np.array_equal(idx, expected_indices), f"Expected {expected_indices}, got {idx}"
 
 
 class MockMouseEvent:
@@ -102,13 +130,15 @@ def selector_class(request):
         (InteractiveEllipseSelector, [0, 0, 1, 1, 1, 0]),
         # Test case for InteractiveLassoSelector
         (InteractiveLassoSelector, [0, 0, 1, 1, 1, 0]),
+        # Test case for InteractiveClickSelector
+        (InteractiveClickSelector, [0, 0, 1, 1, 1, 0]),
     ],
     indirect=["selector_class"],
 )
 def test_interactive_selectors(
     make_napari_viewer, selector_class, expected_color_indices
 ):
-    """Test InteractiveRectangleSelector, InteractiveEllipseSelector, and InteractiveLassoSelector."""
+    """Test InteractiveRectangleSelector, InteractiveEllipseSelector, InteractiveLassoSelector, and InteractiveClickSelector."""
     viewer = make_napari_viewer()
     widget = CanvasWidget(viewer)
     selector = selector_class(widget.axes, widget)
@@ -131,3 +161,7 @@ def test_interactive_selectors(
     ), "Color indices {} do not match expected values {}.".format(
         selector.color_indices, expected_color_indices
     )
+
+
+if __name__ == "__main__":
+    pytest.main([__file__])

src/biaplotter/_version.py

@@ -0,0 +1,34 @@
+# file generated by setuptools-scm
+# don't change, don't track in version control
+
+__all__ = [
+    "__version__",
+    "__version_tuple__",
+    "version",
+    "version_tuple",
+    "__commit_id__",
+    "commit_id",
+]
+
+TYPE_CHECKING = False
+if TYPE_CHECKING:
+    from typing import Tuple
+    from typing import Union
+
+    VERSION_TUPLE = Tuple[Union[int, str], ...]
+    COMMIT_ID = Union[str, None]
+else:
+    VERSION_TUPLE = object
+    COMMIT_ID = object
+
+version: str
+__version__: str
+__version_tuple__: VERSION_TUPLE
+version_tuple: VERSION_TUPLE
+commit_id: COMMIT_ID
+__commit_id__: COMMIT_ID
+
+__version__ = version = '0.4.3.dev0+g5bbac0ba8.d20260114'
+__version_tuple__ = version_tuple = (0, 4, 3, 'dev0', 'g5bbac0ba8.d20260114')
+
+__commit_id__ = commit_id = 'g5bbac0ba8'

src/biaplotter/plotter.py

@@ -14,9 +14,12 @@
 from qtpy.QtGui import QCursor
 
 from biaplotter.artists import Histogram2D, Scatter
-from biaplotter.selectors import (InteractiveEllipseSelector,
-                                  InteractiveLassoSelector,
-                                  InteractiveRectangleSelector)
+from biaplotter.selectors import (
+    InteractiveEllipseSelector,
+    InteractiveLassoSelector,
+    InteractiveRectangleSelector,
+    InteractiveClickSelector,
+)
 
 if TYPE_CHECKING:
     import napari
@@ -53,6 +56,12 @@ class CanvasWidget(BaseNapariMPLWidget):
     The widget includes a selection toolbar with buttons to enable/disable selection tools.
     The selection toolbar includes a color class spinbox to select the class to assign to selections.
     The widget includes artists and selectors to plot data and select points.
+
+    Available selectors:
+        * Lasso
+        * Ellipse
+        * Rectangle
+        * Click (single-point picker)
 
     Parameters
     ----------
@@ -165,6 +174,7 @@ def _initialize_selector_toolbar(self, label_text: str):
         self.class_spinbox: QtColorSpinBox = class_spinbox
         self.show_overlay_button: CustomToolButton = show_overlay_button
 
+
         # Add buttons to the toolbar
         self.selection_toolbar.add_custom_button(
             name="LASSO",
@@ -190,6 +200,14 @@ def _initialize_selector_toolbar(self, label_text: str):
             checked_icon_path=icon_folder_path / "rectangle_checked.png",
             callback=self._on_toggle_button,
         )
+        self.selection_toolbar.add_custom_button(
+            name="CLICK",
+            tooltip="Click to enable/disable single-point selection",
+            default_icon_path=icon_folder_path / "picker.png",
+            checkable=True,
+            checked_icon_path=icon_folder_path / "picker_checked.png",
+            callback=self._on_toggle_button,
+        )
 
         # Add selection tools layout to the main layout
         self.layout().insertLayout(1, self.selection_tools_layout)
@@ -212,6 +230,7 @@ def _initialize_selectors(self):
             InteractiveRectangleSelector
             | InteractiveEllipseSelector
             | InteractiveLassoSelector
+            | InteractiveClickSelector
         ) = None
         self.selectors: dict = {}
         self.add_selector(
@@ -226,6 +245,10 @@ def _initialize_selectors(self):
             "RECTANGLE",
             InteractiveRectangleSelector(self.axes, self),
         )
+        self.add_selector(
+            "CLICK",
+            InteractiveClickSelector(ax=self.axes, canvas_widget=self),
+        )
 
     def _connect_signals(self):
         """

src/biaplotter/selectors.py

@@ -440,6 +440,95 @@ def create_selector(self):
         )
 
 
+# --- Single Click Selector ---
+class BaseClickSelector(Selector):
+    """Base class for creating a single-point (click) selector.
+
+    Inherits all parameters and attributes from Selector.
+    For parameter and attribute details, see the Selector class documentation.
+
+    Parameters
+    ----------
+    ax : plt.Axes
+        axes to which the selector will be applied.
+    data : (N, 2) np.ndarray
+        data to be selected.
+    """
+
+    def __init__(self, ax: plt.Axes, data: np.ndarray = None):
+        super().__init__(ax, data)
+        self.name: str = "Click Selector"
+        self.data = data
+        self._cid = None  # Matplotlib connection id
+
+    def on_select(self, event, threshold: float = 0.025) -> np.ndarray:
+        """Selects the closest point to the click and returns its index, if within a threshold distance.
+
+        Parameters
+        ----------
+        event : MouseEvent
+            The mouse click event.
+        threshold : float, optional
+            Maximum allowed distance from the click to a data point. If None, always select the closest.
+
+        Returns
+        -------
+        np.ndarray or None
+            The index of the selected point (as a 1-element array), or None if no data or too far.
+        """
+        if self._data is None or len(self._data) == 0:
+            return np.array([])
+        if event.xdata is None or event.ydata is None:
+            return np.array([])
+        click_point = np.array([event.xdata, event.ydata])
+        dists = np.linalg.norm(self._data - click_point, axis=1)
+        idx = np.argmin(dists)
+        min_dist = dists[idx]
+
+        # Default threshold: 2.5% of the max plot range
+        xlim = self.ax.get_xlim()
+        ylim = self.ax.get_ylim()
+        max_range = max(xlim[1] - xlim[0], ylim[1] - ylim[0])
+
+        if min_dist > threshold * max_range:
+            return np.array([])# Too far, do not select
+        return np.array([idx])
+
+    @property
+    def data(self) -> np.ndarray:
+        """Gets or sets the data from which points will be selected.
+
+        Returns
+        -------
+        np.ndarray
+            The data from which points will be selected.
+        """
+        return self._data
+
+    @data.setter
+    def data(self, value: np.ndarray):
+        self._data = value
+
+    def create_selector(self):
+        """Creates a click selector by connecting a pick event to the axes canvas."""
+        if self._cid is not None:
+            self.ax.figure.canvas.mpl_disconnect(self._cid)
+        self._cid = self.ax.figure.canvas.mpl_connect("button_press_event", self.on_select)
+        # Assign a dummy selector object for API consistency
+        # There is no actual selector widget for click selection in matplotlib,
+        # it's just the raw event that's used.
+        class DummySelector:
+            def clear(self): pass
+            def disconnect_events(self): pass
+        self._selector = DummySelector()
+
+    def remove(self):
+        """Removes the click selector from the canvas."""
+        if self._cid is not None:
+            self.ax.figure.canvas.mpl_disconnect(self._cid)
+            self._cid = None
+
+
 class Interactive(Selector):
     """Interactive selector class.
 
@@ -771,3 +860,61 @@ def on_select(self, vertices: np.ndarray):
         """
         self.selected_indices = super().on_select(vertices)
         self.apply_selection()
+
+
+# --- Interactive Click Selector ---
+class InteractiveClickSelector(Interactive, BaseClickSelector):
+    """Interactive click selector class.
+
+    Inherits all parameters and attributes from Interactive and BaseClickSelector.
+    To be used as an interactive single-point selector for Scatter, or bin selector for Histogram2D.
+
+    Parameters
+    ----------
+    ax : plt.Axes
+        The axes to which the selector will be applied.
+    canvas_widget : biaplotter.plotter.CanvasWidget
+        The canvas widget to which the selector will be applied.
+    data : (N, 2) np.ndarray, optional
+        The data to be selected.
+
+    Other Parameters
+    ----------------
+    name : str
+        The name of the selector, set to 'Interactive Click Selector' by default.
+    """
+
+    def __init__(
+        self,
+        ax: plt.Axes,
+        canvas_widget: "CanvasWidget",
+        data: np.ndarray = None,
+    ):
+        super().__init__(ax, canvas_widget, data)
+        self.name: str = "Interactive Click Selector"
+
+    def on_select(self, event):
+        """Selects the closest point to the click for Scatter, or all points in the clicked bin for Histogram2D."""
+        artist = self.active_artist
+        if isinstance(artist, Histogram2D):
+            # Find the bin for the click
+            x_edges, y_edges = artist.histogram[1], artist.histogram[2]
+            if event.xdata is None or event.ydata is None:
+                return
+            bin_x = np.digitize(event.xdata, x_edges) - 1
+            bin_y = np.digitize(event.ydata, y_edges) - 1
+            if 0 <= bin_x < len(x_edges) - 1 and 0 <= bin_y < len(y_edges) - 1:
+                mask = (
+                    (artist.data[:, 0] >= x_edges[bin_x])
+                    & (artist.data[:, 0] < x_edges[bin_x + 1])
+                    & (artist.data[:, 1] >= y_edges[bin_y])
+                    & (artist.data[:, 1] < y_edges[bin_y + 1])
+                )
+                indices = np.where(mask)[0]
+                if len(indices) > 0:
+                    self.selected_indices = indices
+                    self.apply_selection()
+        else:
+            indices = super().on_select(event)
+            self.selected_indices = indices
+            self.apply_selection()