implemented hover feature for other backends; fixed string list; adde… (#9)

* implemented hover feature for other backends; fixed string list; added dict

* fix linter issues

* more linter issues

---------

Co-authored-by: Yanshi Chen <ychen288@u.rochester.edu>

Author: lucychencys

galleries/examples/event_handling/hover_event_demo.py

@@ -19,6 +19,9 @@
 * list of string literals - hovering is enabled, and hovering over a point
   displays the corresponding string literal.
 
+* dictionary - hovering is enabled, and hovering over a point
+  displays the string literal corresponding to the coordinate tuple.
+
 * function - if hover is callable, it is a user supplied function which
   takes a ``mouseevent`` object (see below), and returns a tuple of transformed
   coordinates
@@ -69,16 +72,26 @@ def hover_handler(event):
 from numpy.random import rand
 
 fig, ax = plt.subplots()
-plt.ylabel('some numbers')
 
 ax.plot(rand(3), 'o', hover=['London', 'Paris', 'Barcelona'])
 plt.show()
 
+# %%
+# Hover with dictionary data
+# --------------------------------
+fig, ax = plt.subplots()
+x = rand(3)
+y = rand(3)
+ax.plot(x, y, 'o', hover={
+    (x[0], y[0]): "London",
+    (x[1], y[1]): "Paris",
+    (x[2], y[2]): "Barcelona"})
+plt.show()
+
 # %%
 # Hover with a callable transformation function
 # ---------------------------------------------
 fig, ax = plt.subplots()
-plt.ylabel('some numbers')
 
 
 def user_defined_function(event):

lib/matplotlib/artist.py

@@ -653,10 +653,18 @@ def set_hover(self, hover):
               function which sets the hover message to be displayed.
 
             - A list: If hover is a list of string literals, each string represents
-              an additional information assigned to each data point. These arbitrary
-              data labels will appear as a tooltip in the bottom right hand corner
+              an additional information assigned to each data point. These data labels
+              will appear as a tooltip in the bottom right hand corner
               of the screen when the cursor is detected to be hovering over a data
-              point that corresponds with one of the data labels.
+              point that corresponds with the data labels in the same order that
+              was passed in.
+
+            - A dictionary: If hover is a dictionary of key value paris, each key
+              represents a tuple of x and y coordinate and each value represnets
+              additional information assigned to each data point. These data labels
+              will appear as a tooltip in the bottom right hand corner of the
+              screen when the cursor is detected to be hovering over a data point
+              that corresponds with one of the data labels.
         """
         self._hover = hover
 

lib/matplotlib/artist.pyi

@@ -83,11 +83,12 @@ class Artist:
         hover: None
         | bool
         | list[str]
+        | dict[tuple[float, float], str]
         | Callable[[Artist, MouseEvent], tuple[bool, dict[Any, Any]]],
     ) -> None: ...
     def get_hover(
         self,
-    ) -> None | bool | list[str] | Callable[
+    ) -> None | bool | list[str] | dict[tuple[float, float], str] | Callable[
         [Artist, MouseEvent], tuple[bool, dict[Any, Any]]
     ]: ...
     def get_url(self) -> str | None: ...

lib/matplotlib/backend_bases.py

@@ -3015,25 +3015,26 @@ def _nonrect(self, x):
         return not isinstance(x, Rectangle)
 
     def _tooltip_list(self, event, hover):
-        import matplotlib.pyplot as plt
-        lines = plt.gca().get_lines()
-        num_of_points = 0
-        for line in lines:
-            num_of_points += 1
-        if num_of_points >= len(hover):
+        lines = self.canvas.figure.gca().get_lines()[0]
+        coor_data = list(zip(lines.get_xdata(), lines.get_ydata()))
+
+        if len(coor_data) != len(hover):
             raise ValueError("""Number of data points
-            does not match up with number of labels""")
+             does not match up with number of labels""")
         else:
-            mouse_x = event.xdata
-            mouse_y = event.ydata
-            for line in lines:
-                x_data = line.get_xdata()
-                y_data = line.get_ydata()
-                for i in range(len(x_data)):
-                    distance = ((event.xdata - x_data[i])**2
-                                + (event.ydata - y_data[i])**2)**0.5
-                    if distance < 0.05:
-                        return "Data Label: " + hover[i]
+            distances = []
+            for a in coor_data:
+                distances.append(((event.xdata - a[0])**2 +
+                                  (event.ydata - a[1])**2)**0.5)
+            if (min(distances) < 0.05):
+                return f"Data Label: {hover[distances.index(min(distances))]}"
+
+    def _tooltip_dict(self, event, hover):
+        distances = {}
+        for a in hover.keys():
+            distances[a] = ((event.xdata - a[0])**2 + (event.ydata - a[1])**2)**0.5
+        if (min(distances.values()) < 0.05):
+            return f"Data Label: {hover[min(distances, key=distances.get)]}"
 
     def mouse_move(self, event):
         self._update_cursor(event)
@@ -3050,6 +3051,8 @@ def mouse_move(self, event):
                             self.set_hover_message(hover(event))
                         elif type(hover) == list:
                             self.set_hover_message(self._tooltip_list(event, hover))
+                        elif type(hover) == dict:
+                            self.set_hover_message(self._tooltip_dict(event, hover))
                         else:
                             self.set_hover_message(self._mouse_event_to_message(event))
                 else:

lib/matplotlib/backends/_backend_gtk.py

@@ -274,6 +274,10 @@ def set_message(self, s):
         escaped = GLib.markup_escape_text(s)
         self.message.set_markup(f'<small>{escaped}</small>')
 
+    def set_hover_message(self, s):
+        escaped = GLib.markup_escape_text(s)
+        self.hover_message.set_markup(f'<small>{escaped}</small>')
+
     def draw_rubberband(self, event, x0, y0, x1, y1):
         height = self.canvas.figure.bbox.height
         y1 = height - y1

lib/matplotlib/backends/backend_gtk3.py

@@ -395,6 +395,11 @@ def __init__(self, toolmanager):
         self._message = Gtk.Label()
         self._message.set_justify(Gtk.Justification.RIGHT)
         self.pack_end(self._message, False, False, 0)
+
+        self.hover_message = Gtk.Label()
+        self.hover_message.set_justify(Gtk.Justification.RIGHT)
+        self.pack_end(self.hover_message, False, False, 0)
+
         self.show_all()
         self._groups = {}
         self._toolitems = {}
@@ -465,6 +470,9 @@ def _add_separator(self):
     def set_message(self, s):
         self._message.set_label(s)
 
+    def set_hover_message(self, s):
+        self._hover_message.set_label(s)
+
 
 @backend_tools._register_tool_class(FigureCanvasGTK3)
 class SaveFigureGTK3(backend_tools.SaveFigureBase):

lib/matplotlib/backends/backend_gtk4.py

@@ -328,6 +328,10 @@ def __init__(self, canvas):
         self.message.set_justify(Gtk.Justification.RIGHT)
         self.append(self.message)
 
+        self.hover_message = Gtk.Label()
+        self.hover_message.set_justify(Gtk.Justification.RIGHT)
+        self.append(self.hover_message)
+
         _NavigationToolbar2GTK.__init__(self, canvas)
 
     def save_figure(self, *args):
@@ -493,6 +497,9 @@ def _add_separator(self):
     def set_message(self, s):
         self._message.set_label(s)
 
+    def set_hover_message(self, s):
+        self._hover_message.set_label(s)
+
 
 @backend_tools._register_tool_class(FigureCanvasGTK4)
 class SaveFigureGTK4(backend_tools.SaveFigureBase):

lib/matplotlib/backends/backend_qt.py

@@ -677,9 +677,19 @@ def __init__(self, canvas, parent=None, coordinates=True):
                 _enum("QtWidgets.QSizePolicy.Policy").Expanding,
                 _enum("QtWidgets.QSizePolicy.Policy").Ignored,
             ))
+            self.hover_message = QtWidgets.QLabel("", self)
+            self.hover_message.setAlignment(QtCore.Qt.AlignmentFlag(
+                _to_int(_enum("QtCore.Qt.AlignmentFlag").AlignRight) |
+                _to_int(_enum("QtCore.Qt.AlignmentFlag").AlignVCenter)))
+            self.hover_message.setSizePolicy(QtWidgets.QSizePolicy(
+                _enum("QtWidgets.QSizePolicy.Policy").Expanding,
+                _enum("QtWidgets.QSizePolicy.Policy").Ignored,
+            ))
+            labelActionHover = self.addWidget(self.hover_message)
+            labelActionHover.setVisible(True)
+
             labelAction = self.addWidget(self.locLabel)
             labelAction.setVisible(True)
-
         NavigationToolbar2.__init__(self, canvas)
 
     def _icon(self, name):
@@ -756,6 +766,11 @@ def set_message(self, s):
         if self.coordinates:
             self.locLabel.setText(s)
 
+    def set_hover_message(self, s):
+        self.message.emit(s)
+        if self.coordinates:
+            self.hover_message.setText(s)
+
     def draw_rubberband(self, event, x0, y0, x1, y1):
         height = self.canvas.figure.bbox.height
         y1 = height - y1

lib/matplotlib/backends/backend_wx.py

@@ -1051,6 +1051,8 @@ def __init__(self, canvas, coordinates=True, *, style=wx.TB_BOTTOM):
             self.AddStretchableSpace()
             self._label_text = wx.StaticText(self, style=wx.ALIGN_RIGHT)
             self.AddControl(self._label_text)
+            self._hover_message = wx.StaticText(self, style=wx.ALIGN_LEFT)
+            self.AddControl(self._hover_message)
 
         self.Realize()
 
@@ -1143,6 +1145,10 @@ def set_message(self, s):
         if self._coordinates:
             self._label_text.SetLabel(s)
 
+    def set_hover_message(self, s):
+        if self._coordinates:
+            self._hover_message.SetLabel(s)
+
     def set_history_buttons(self):
         can_backward = self._nav_stack._pos > 0
         can_forward = self._nav_stack._pos < len(self._nav_stack._elements) - 1
@@ -1163,6 +1169,10 @@ def __init__(self, toolmanager, parent=None, style=wx.TB_BOTTOM):
         self._space = self.AddStretchableSpace()
         self._label_text = wx.StaticText(self, style=wx.ALIGN_RIGHT)
         self.AddControl(self._label_text)
+
+        self._hover_message = wx.StaticText(self, style=wx.ALIGN_LEFT)
+        self.AddControl(self._hover_message)
+
         self._toolitems = {}
         self._groups = {}  # Mapping of groups to the separator after them.
 
@@ -1240,6 +1250,9 @@ def remove_toolitem(self, name):
     def set_message(self, s):
         self._label_text.SetLabel(s)
 
+    def set_hover_message(self, s):
+        self._hover_message.SetLabel(s)
+
 
 @backend_tools._register_tool_class(_FigureCanvasWxBase)
 class ConfigureSubplotsWx(backend_tools.ConfigureSubplotsBase):