fix: Trend indicator not working with date_range x-axis

panel/tests/widgets/test_trend_indicator.py

@@ -1,5 +1,8 @@
 import random
 
+import numpy as np
+import pandas as pd
+
 from panel import (
     Column, Param, Row, WidgetBox, state,
 )
@@ -26,6 +29,21 @@ def test_trend_auto_value(document, comm):
     assert model.value_change == ((4000/3900) - 1)
 
 
+def test_trend_date_range_x_axis(document, comm):
+    data = pd.DataFrame({
+        "Date": pd.date_range(start="2020-01-01", periods=5, freq="ME"),
+        "Sales": [100, 120, 150, 130, 110],
+    })
+
+    trend = Trend(data=data, plot_x="Date", plot_y="Sales")
+    model = trend.get_root(document, comm)
+
+    x_data = model.source.data["Date"]
+    assert len(x_data) == 5
+    np.testing.assert_array_equal(x_data, np.arange(5, dtype=float))
+    assert model.value == 110
+
+
 def test_trend_auto_value_stream(document, comm):
     data = {"x": [1, 2, 3, 4, 5], "y": [3800, 3700, 3800, 3900, 4000]}
 

panel/widgets/indicators.py

@@ -1174,7 +1174,14 @@ def _get_data(self):
             return None, {self.plot_x: [], self.plot_y: []}
         elif isinstance(self.data, dict):
             return self.data, self.data
-        return self.data, ColumnDataSource.from_df(self.data)
+        processed = ColumnDataSource.from_df(self.data)
+        if (
+            self.plot_x in getattr(self.data, 'columns', []) and
+            np.issubdtype(self.data[self.plot_x].dtype, np.datetime64)
+        ):
+            processed = dict(processed)
+            processed[self.plot_x] = np.arange(len(self.data), dtype=float)
+        return self.data, processed
 
     def _init_params(self):
         props = super()._init_params()