Add MultiAxisTap stream

holoviews/plotting/bokeh/callbacks.py

@@ -50,6 +50,7 @@
     Lasso,
     MouseEnter,
     MouseLeave,
+    MultiAxisTap,
     PanEnd,
     PlotReset,
     PlotSize,
@@ -781,6 +782,54 @@ def _process_out_of_bounds(self, value, start, end):
         return value
 
 
+class MultiAxisTapCallback(TapCallback):
+    """
+    Returns the mouse x/y-positions on tap event.
+    """
+
+    attributes = {'x': 'cb_obj.x', 'y': 'cb_obj.y'}
+
+    def _process_msg(self, msg):
+        x_range = self.plot.handles.get('x_range')
+        y_range = self.plot.handles.get('y_range')
+        extra_x = list(self.plot.handles.get('extra_x_ranges', {}).values())
+        extra_y = list(self.plot.handles.get('extra_y_ranges', {}).values())
+        xaxis = self.plot.handles.get('xaxis')
+        yaxis = self.plot.handles.get('yaxis')
+
+        # Compute x/y position relative to first axis
+        x, y = msg['x'], msg['y']
+        x0, x1 = x_range.start, x_range.end
+        y0, y1 = y_range.start, y_range.end
+        if isinstance(xaxis, DatetimeAxis):
+            x = convert_timestamp(x)
+            if isinstance(x0, (float, int)):
+                x0 = convert_timestamp(x0)
+            if isinstance(x1, (float, int)):
+                x1 = convert_timestamp(x1)
+        if isinstance(yaxis, DatetimeAxis):
+            y = convert_timestamp(y)
+            if isinstance(y0, (float, int)):
+                y0 = convert_timestamp(y0)
+            if isinstance(y1, (float, int)):
+                y1 = convert_timestamp(y1)
+        xs, ys = {x_range.name: x}, {y_range.name: y}
+        xspan, yspan = x1 - x0, y1 - y0
+        xfactor, yfactor = (x-x0) / xspan, (y-y0) / yspan
+
+        # Use computed factors to compute x/y position on other axes
+        for values, factor, ranges, axis in (
+            (xs, xfactor, extra_x, xaxis),
+            (ys, yfactor, extra_y, yaxis)
+        ):
+            for rng in ranges:
+                value = rng.start + (rng.end-rng.start) * factor
+                if isinstance(axis, DatetimeAxis) and isinstance(value, (float, int)):
+                    value = convert_timestamp(value)
+                values[rng.name] = value
+
+        return {'xs': xs, 'ys': ys}
+
 
 class SingleTapCallback(TapCallback):
     """
@@ -1585,5 +1634,6 @@ def initialize(self, plot_id=None):
     FreehandDraw: FreehandDrawCallback,
     PolyDraw    : PolyDrawCallback,
     PolyEdit    : PolyEditCallback,
-    SelectMode  : SelectModeCallback
+    SelectMode  : SelectModeCallback,
+    MultiAxisTap: MultiAxisTapCallback
 })

holoviews/plotting/bokeh/element.py

@@ -802,20 +802,27 @@ def _axis_props(self, plots, subplots, element, ranges, pos, *, dim=None,
             if dim_range:
                 self._shared[shared_name] = True
 
+        # If we have a single dimension grab it so it can be set as the Range name
+        name = None
+        if dim:
+            name = dim.name
+        elif dims and len(dims) == 1:
+            name = dims[0].name
+
         if self._shared.get(shared_name) and not dim:
             pass
         elif categorical:
             axis_type = 'auto'
-            dim_range = FactorRange()
+            dim_range = FactorRange(name=name)
         elif None in [v0, v1] or any(
             True if isinstance(el, (str, bytes)+util.cftime_types)
             else not util.isfinite(el) for el in [v0, v1]
         ):
-            dim_range = range_type()
+            dim_range = range_type(name=name)
         elif issubclass(range_type, FactorRange):
-            dim_range = range_type(name=dim.name if dim else None)
+            dim_range = range_type(name=name)
         else:
-            dim_range = range_type(start=v0, end=v1, name=dim.name if dim else None)
+            dim_range = range_type(start=v0, end=v1, name=name)
 
         if not dim_range.tags and specs is not None:
             dim_range.tags.append(specs)

holoviews/streams.py

@@ -1358,6 +1358,18 @@ class Tap(PointerXY):
            Pointer position along the y-axis in data coordinates""")
 
 
+class MultiAxisTap(LinkedStream):
+    """
+    The x/y-positions of a tap or click in data coordinates.
+    """
+
+    xs = param.Dict(default=None, constant=True, doc="""
+           Pointer positions along the x-axes in data coordinates""")
+
+    ys = param.Dict(default=None, constant=True, doc="""
+           Pointer positions along the y-axes in data coordinates""")
+
+
 class DoubleTap(PointerXY):
     """
     The x/y-position of a double-tap or -click in data coordinates.

holoviews/tests/ui/bokeh/test_callback.py

@@ -1,11 +1,12 @@
 import numpy as np
+import pandas as pd
 import panel as pn
 import pytest
 
 import holoviews as hv
 from holoviews import Curve, DynamicMap, Scatter
 from holoviews.plotting.bokeh.util import bokeh34
-from holoviews.streams import BoundsX, BoundsXY, BoundsY, Lasso, RangeXY
+from holoviews.streams import BoundsX, BoundsXY, BoundsY, Lasso, MultiAxisTap, RangeXY
 
 from .. import expect, wait_until
 
@@ -164,6 +165,54 @@ def test_multi_axis_rangexy(serve_hv):
     ), page)
 
 
+@pytest.mark.usefixtures("bokeh_backend")
+def test_multi_axis_tap(serve_hv):
+    c1 = Curve(np.arange(10).cumsum(), vdims='y1')
+    c2 = Curve(np.arange(20).cumsum(), vdims='y2')
+
+    overlay = (c1 * c2).opts(multi_y=True)
+
+    s = MultiAxisTap(source=overlay)
+
+    page = serve_hv(overlay)
+
+    hv_plot = page.locator('.bk-events')
+
+    expect(hv_plot).to_have_count(1)
+
+    hv_plot.click()
+
+    def test():
+        assert s.xs == {'x': 11.560240963855422}
+        assert s.ys == {'y1': 18.642857142857146, 'y2': 78.71428571428572}
+
+    wait_until(test, page)
+
+
+@pytest.mark.usefixtures("bokeh_backend")
+def test_multi_axis_tap_datetime(serve_hv):
+    c1 = Curve((pd.date_range('2024-01-01', '2024-01-10'), np.arange(10).cumsum()), vdims='y1')
+    c2 = Curve((pd.date_range('2024-01-01', '2024-01-20'), np.arange(20).cumsum()), vdims='y2')
+
+    overlay = (c1 * c2).opts(multi_y=True)
+
+    s = MultiAxisTap(source=overlay)
+
+    page = serve_hv(overlay)
+
+    hv_plot = page.locator('.bk-events')
+
+    expect(hv_plot).to_have_count(1)
+
+    hv_plot.click()
+
+    def test():
+        assert s.xs == {'x': np.datetime64('2024-01-12T13:26:44.819277')}
+        assert s.ys == {'y1': 18.13070539419087, 'y2': 76.551867219917}
+
+    wait_until(test, page)
+
+
 @pytest.mark.usefixtures("bokeh_backend")
 def test_bind_trigger(serve_hv):
     # Regression test for https://github.com/holoviz/holoviews/issues/6013