From 7d6fc21b5247b9bff975d869f479e3a2c6da5c71 Mon Sep 17 00:00:00 2001
From: Neil Vaytet <neil.vaytet@ess.eu>
Date: Wed, 4 Feb 2026 23:32:11 +0100
Subject: [PATCH 1/2] fix boundaries and label of slider with bin edge coord

---
 src/plopp/widgets/slice.py | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/src/plopp/widgets/slice.py b/src/plopp/widgets/slice.py
index 6f85cd62..c8873ab3 100644
--- a/src/plopp/widgets/slice.py
+++ b/src/plopp/widgets/slice.py
@@ -34,6 +34,7 @@ def __init__(
             'readout': False,
             'layout': {"width": "15.2em", "margin": "0px 0px 0px 10px"},
         }
+        self._is_bin_edges = coord.sizes[dim] > size
         self.dim_label = ipw.Label(value=dim)
         self.slider = slider_constr(**widget_args)
         self.continuous_update = ipw.Checkbox(
@@ -42,9 +43,7 @@ def __init__(
             indent=False,
             layout={"width": "1.52em"},
         )
-        self.label = ipw.Label(
-            value=coord_element_to_string(coord[dim, self.slider.value])
-        )
+        self.label = ipw.Label()
         ipw.jslink(
             (self.continuous_update, 'value'), (self.slider, 'continuous_update')
         )
@@ -64,6 +63,7 @@ def __init__(
 
         self.dim = dim
         self.coord = coord
+        self._update_label({"new": self.slider.value})
         self.slider.observe(self._update_label, names='value')
 
         super().__init__([ipw.HBox(children)])
@@ -73,7 +73,13 @@ def _update_label(self, change: dict[str, Any]):
         Update the readout label with the coordinate value, instead of the integer
         readout index.
         """
-        self.label.value = coord_element_to_string(self.coord[self.dim, change['new']])
+        inds = change["new"]
+        if self._is_bin_edges:
+            if isinstance(inds, tuple):
+                inds = (inds[0], inds[1] + 1)
+            else:
+                inds = (inds, inds + 1)
+        self.label.value = coord_element_to_string(self.coord[self.dim, inds])
 
     @property
     def value(self) -> int | tuple[int, int]:
@@ -180,6 +186,6 @@ def slice_dims(data_array: sc.DataArray, slices: dict[str, slice]) -> sc.DataArr
     out = data_array
     for dim, sl in slices.items():
         if isinstance(sl, tuple):
-            sl = slice(*sl)
+            sl = slice(sl[0], sl[1] + 1)
         out = out[dim, sl]
     return out

From c3d427b2f79a2ed8e76f83f5d878039b68934dda Mon Sep 17 00:00:00 2001
From: Neil Vaytet <neil.vaytet@ess.eu>
Date: Thu, 5 Feb 2026 11:50:49 +0100
Subject: [PATCH 2/2] fix test and clarify slicing behaviour

---
 src/plopp/widgets/slice.py  | 2 ++
 tests/widgets/slice_test.py | 5 ++++-
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/plopp/widgets/slice.py b/src/plopp/widgets/slice.py
index c8873ab3..39ef8ce8 100644
--- a/src/plopp/widgets/slice.py
+++ b/src/plopp/widgets/slice.py
@@ -186,6 +186,8 @@ def slice_dims(data_array: sc.DataArray, slices: dict[str, slice]) -> sc.DataArr
     out = data_array
     for dim, sl in slices.items():
         if isinstance(sl, tuple):
+            # Include the stop index in the slice, as we expect both slider handles to
+            # be inclusive.
             sl = slice(sl[0], sl[1] + 1)
         out = out[dim, sl]
     return out
diff --git a/tests/widgets/slice_test.py b/tests/widgets/slice_test.py
index 96d3053f..47208cfc 100644
--- a/tests/widgets/slice_test.py
+++ b/tests/widgets/slice_test.py
@@ -60,5 +60,8 @@ def test_slice_dims():
 def test_range_slice_dims():
     da = data_array(ndim=3)
     slices = {'xx': (8, 9), 'yy': (7, 10)}
-    expected = da['xx', slice(*slices['xx'])]['yy', slice(*slices['yy'])]
+    # Note that we want to include the stop index in the slice
+    expected = da['xx', slices['xx'][0] : slices['xx'][1] + 1][
+        'yy', slices['yy'][0] : slices['yy'][1] + 1
+    ]
     assert identical(slice_dims().func(da, slices=slices), expected)