From 043f7fcaabc72021f9256b21efec5bc979e9ef0f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Fri, 8 Dec 2023 19:19:01 +0100
Subject: [PATCH 01/28] Add viewport downsample algorithm

---
 holoviews/operation/downsample.py | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index f7b2e75c82..cfd9d8911d 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -147,10 +147,14 @@ def _nth_point(x, y, n_out):
     n_samples = len(x)
     return np.arange(0, n_samples, max(1, math.ceil(n_samples / n_out)))
 
+def _viewport(x, y, n_out):
+    return slice(0, len(x))
+
 
 _ALGORITHMS = {
     'lttb': _lttb,
-    'nth': _nth_point
+    'nth': _nth_point,
+    'viewport': _viewport,
 }
 
 
@@ -164,7 +168,7 @@ class downsample1d(ResampleOperation1D):
         - `nth`: Selects every n-th point.
     """
 
-    algorithm = param.Selector(default='lttb', objects=['lttb', 'nth'])
+    algorithm = param.Selector(default='lttb', objects=list(_ALGORITHMS))
 
     def _process(self, element, key=None):
         if isinstance(element, (Overlay, NdOverlay)):
@@ -176,7 +180,7 @@ def _process(self, element, key=None):
             return element.clone(elements)
 
         if self.p.x_range:
-            element = element[slice(*self.p.x_range)]
+            element = element[slice(self.p.x_range[0], self.p.x_range[1] + 1)]
         if len(element) <= self.p.width:
             return element
         xs, ys = (element.dimension_values(i) for i in range(2))

From bf428910a55dc05aa6588e2ebed64cc724984deb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Tue, 19 Dec 2023 09:56:43 +0100
Subject: [PATCH 02/28] pop non relevant stream ranges in RangeX and RangeY

---
 holoviews/streams.py | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/holoviews/streams.py b/holoviews/streams.py
index 309b4ac153..75f66af7af 100644
--- a/holoviews/streams.py
+++ b/holoviews/streams.py
@@ -1480,6 +1480,10 @@ class RangeX(LinkedStream):
     x_range = param.Tuple(default=None, length=2, constant=True, doc="""
       Range of the x-axis of a plot in data coordinates""")
 
+    def _set_stream_parameters(self, **kwargs):
+        kwargs.pop("y_range", None)
+        super()._set_stream_parameters(**kwargs)
+
 
 class RangeY(LinkedStream):
     """
@@ -1489,6 +1493,10 @@ class RangeY(LinkedStream):
     y_range = param.Tuple(default=None, length=2, constant=True, doc="""
       Range of the y-axis of a plot in data coordinates""")
 
+    def _set_stream_parameters(self, **kwargs):
+        kwargs.pop("x_range", None)
+        super()._set_stream_parameters(**kwargs)
+
 
 class BoundsXY(LinkedStream):
     """

From 914197943fabe4699c925d02917988a554864e30 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Tue, 19 Dec 2023 09:58:29 +0100
Subject: [PATCH 03/28] Rough implementation of finding first value outside of
 range

---
 holoviews/operation/downsample.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index cfd9d8911d..67b0b1ba71 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -180,7 +180,8 @@ def _process(self, element, key=None):
             return element.clone(elements)
 
         if self.p.x_range:
-            element = element[slice(self.p.x_range[0], self.p.x_range[1] + 1)]
+            # TODO: find a better way to get the first value outside the range
+            element = element[slice(0.95 * self.p.x_range[0], self.p.x_range[1] * 1.05)]
         if len(element) <= self.p.width:
             return element
         xs, ys = (element.dimension_values(i) for i in range(2))

From 0943eeae6ebae6bb48afc33f727988878bdea8e2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Tue, 19 Dec 2023 09:58:42 +0100
Subject: [PATCH 04/28] Remove unnessary 0

---
 holoviews/operation/downsample.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index 67b0b1ba71..6a3956a97f 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -148,7 +148,7 @@ def _nth_point(x, y, n_out):
     return np.arange(0, n_samples, max(1, math.ceil(n_samples / n_out)))
 
 def _viewport(x, y, n_out):
-    return slice(0, len(x))
+    return slice(len(x))
 
 
 _ALGORITHMS = {

From 45d89daa2f97bdbaa66c3fe8c8e2fd1c4694195b Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Tue, 19 Dec 2023 09:58:56 +0100
Subject: [PATCH 05/28] Add hack to work with xlim

---
 holoviews/operation/downsample.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index 6a3956a97f..98f9c2923d 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -171,6 +171,7 @@ class downsample1d(ResampleOperation1D):
     algorithm = param.Selector(default='lttb', objects=list(_ALGORITHMS))
 
     def _process(self, element, key=None):
+        self.p.x_range = self.p.x_range or element.opts.get().kwargs.get("xlim")  # hack
         if isinstance(element, (Overlay, NdOverlay)):
             _process = partial(self._process, key=key)
             if isinstance(element, Overlay):

From b2311b6a0ebcd2946a122140f815618eb71a84ef Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Tue, 19 Dec 2023 10:02:15 +0100
Subject: [PATCH 06/28] Use slice instead of np.arange for nth

---
 holoviews/operation/downsample.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index 98f9c2923d..d9c68860ea 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -142,10 +142,10 @@ def _nth_point(x, y, n_out):
         y (np.ndarray): The y-values of the data.
         n_out (int): The number of output points.
     Returns:
-        np.array: The indexes of the selected datapoints.
+        slice: The slice of selected datapoints.
     """
     n_samples = len(x)
-    return np.arange(0, n_samples, max(1, math.ceil(n_samples / n_out)))
+    return slice(0, n_samples, max(1, math.ceil(n_samples / n_out)))
 
 def _viewport(x, y, n_out):
     return slice(len(x))

From e0ffefdcf0574d24889a1fa23add18c723184e35 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Tue, 19 Dec 2023 10:23:12 +0100
Subject: [PATCH 07/28] Improve detection first values outside of viewport

---
 holoviews/operation/downsample.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index d9c68860ea..e5c575f247 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -181,8 +181,9 @@ def _process(self, element, key=None):
             return element.clone(elements)
 
         if self.p.x_range:
-            # TODO: find a better way to get the first value outside the range
-            element = element[slice(0.95 * self.p.x_range[0], self.p.x_range[1] * 1.05)]
+            xs = element.dimension_values(0)
+            x0, x1 = (np.argmin(np.abs(xs-coord)) for coord in self.p.x_range)
+            element = element.iloc[max(x0 - 1, 0):(x1 + 2)]
         if len(element) <= self.p.width:
             return element
         xs, ys = (element.dimension_values(i) for i in range(2))

From d033ca08825c5500ea3c4e7d7fa1810ed0b6d992 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Wed, 20 Dec 2023 09:38:46 +0100
Subject: [PATCH 08/28] Use boolean logic instead

---
 holoviews/operation/downsample.py | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index e5c575f247..6582665343 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -181,9 +181,12 @@ def _process(self, element, key=None):
             return element.clone(elements)
 
         if self.p.x_range:
-            xs = element.dimension_values(0)
-            x0, x1 = (np.argmin(np.abs(xs-coord)) for coord in self.p.x_range)
-            element = element.iloc[max(x0 - 1, 0):(x1 + 2)]
+            mask = element.dataset.interface.select_mask(element.dataset, {element.kdims[0]: self.p.x_range})
+            extra = mask[1:] ^ mask[:-1]
+            mask[1:] |= extra
+            mask[:-1] |= extra
+            element = element[mask]
+
         if len(element) <= self.p.width:
             return element
         xs, ys = (element.dimension_values(i) for i in range(2))

From fef1b73e36cba5c720af1282ffd591b07c6c9ff2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Wed, 20 Dec 2023 11:11:34 +0100
Subject: [PATCH 09/28] Add select_mask_neighbor

---
 holoviews/core/data/cudf.py       | 12 ++++++++++++
 holoviews/core/data/dask.py       | 12 ++++++++++++
 holoviews/core/data/ibis.py       | 12 ++++++++++++
 holoviews/core/data/interface.py  | 15 +++++++++++++++
 holoviews/operation/downsample.py | 13 +++++++++----
 5 files changed, 60 insertions(+), 4 deletions(-)

diff --git a/holoviews/core/data/cudf.py b/holoviews/core/data/cudf.py
index 36af1ac49e..455a177183 100644
--- a/holoviews/core/data/cudf.py
+++ b/holoviews/core/data/cudf.py
@@ -231,6 +231,18 @@ def select_mask(cls, dataset, selection):
                 mask &= new_mask
         return mask
 
+    @classmethod
+    def _select_mask_neighbor(cls, dataset, selection):
+        """Runs select mask and expand the True values to include its neighbors
+
+        Example
+
+        select_mask =          [False, False, True, True, False, False]
+        select_mask_neighbor = [False, True,  True, True, True,  False]
+
+        """
+        raise NotImplementedError
+
     @classmethod
     def select(cls, dataset, selection_mask=None, **selection):
         df = dataset.data
diff --git a/holoviews/core/data/dask.py b/holoviews/core/data/dask.py
index 5b1160220b..b984947aa4 100644
--- a/holoviews/core/data/dask.py
+++ b/holoviews/core/data/dask.py
@@ -162,6 +162,18 @@ def select(cls, dataset, selection_mask=None, **selection):
             return df[dataset.vdims[0].name].compute().iloc[0]
         return df
 
+    @classmethod
+    def _select_mask_neighbor(cls, dataset, selection):
+        """Runs select mask and expand the True values to include its neighbors
+
+        Example
+
+        select_mask =          [False, False, True, True, False, False]
+        select_mask_neighbor = [False, True,  True, True, True,  False]
+
+        """
+        raise NotImplementedError
+
     @classmethod
     def groupby(cls, dataset, dimensions, container_type, group_type, **kwargs):
         index_dims = [dataset.get_dimension(d) for d in dimensions]
diff --git a/holoviews/core/data/ibis.py b/holoviews/core/data/ibis.py
index 691a55d26c..f904995d07 100644
--- a/holoviews/core/data/ibis.py
+++ b/holoviews/core/data/ibis.py
@@ -427,6 +427,18 @@ def select_mask(cls, dataset, selection):
                 predicates.append(column == object)
         return predicates
 
+    @classmethod
+    def _select_mask_neighbor(cls, dataset, selection):
+        """Runs select mask and expand the True values to include its neighbors
+
+        Example
+
+        select_mask =          [False, False, True, True, False, False]
+        select_mask_neighbor = [False, True,  True, True, True,  False]
+
+        """
+        raise NotImplementedError
+
     @classmethod
     def sample(cls, dataset, samples=None):
         import ibis
diff --git a/holoviews/core/data/interface.py b/holoviews/core/data/interface.py
index 0a60552f9b..cdd3e151a2 100644
--- a/holoviews/core/data/interface.py
+++ b/holoviews/core/data/interface.py
@@ -377,6 +377,21 @@ def select_mask(cls, dataset, selection):
                     mask &= index_mask
         return mask
 
+    @classmethod
+    def _select_mask_neighbor(cls, dataset, selection):
+        """Runs select mask and expand the True values to include its neighbors
+
+        Example
+
+        select_mask =          [False, False, True, True, False, False]
+        select_mask_neighbor = [False, True,  True, True, True,  False]
+
+        """
+        mask = cls.select_mask(dataset, selection)
+        extra = mask[1:] ^ mask[:-1]
+        mask[1:] |= extra
+        mask[:-1] |= extra
+        return mask
 
     @classmethod
     def indexed(cls, dataset, selection):
diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index 6582665343..a863909faf 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -181,10 +181,15 @@ def _process(self, element, key=None):
             return element.clone(elements)
 
         if self.p.x_range:
-            mask = element.dataset.interface.select_mask(element.dataset, {element.kdims[0]: self.p.x_range})
-            extra = mask[1:] ^ mask[:-1]
-            mask[1:] |= extra
-            mask[:-1] |= extra
+            try:
+                mask = element.dataset.interface._select_mask_neighbor(
+                    element.dataset, {element.kdims[0]: self.p.x_range}
+                )
+            except NotImplementedError:
+                mask = slice(*self.p.x_range)
+            except Exception:
+                self.param.warning("Could not apply neighbor mask to downsample1d.")
+                mask = slice(*self.p.x_range)
             element = element[mask]
 
         if len(element) <= self.p.width:

From d226e6ff87a5c25f539b9ed5d034d69c56b3d341 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Wed, 20 Dec 2023 11:34:20 +0100
Subject: [PATCH 10/28] Add _select_mask_neighbor to dask interface

---
 holoviews/core/data/dask.py | 9 ++++++++-
 1 file changed, 8 insertions(+), 1 deletion(-)

diff --git a/holoviews/core/data/dask.py b/holoviews/core/data/dask.py
index b984947aa4..50e1257287 100644
--- a/holoviews/core/data/dask.py
+++ b/holoviews/core/data/dask.py
@@ -154,6 +154,8 @@ def select_mask(cls, dataset, selection):
     def select(cls, dataset, selection_mask=None, **selection):
         df = dataset.data
         if selection_mask is not None:
+            if hasattr(df, "__array__"):
+                return df.loc[selection_mask]
             return df[selection_mask]
         selection_mask = cls.select_mask(dataset, selection)
         indexed = cls.indexed(dataset, selection)
@@ -172,7 +174,12 @@ def _select_mask_neighbor(cls, dataset, selection):
         select_mask_neighbor = [False, True,  True, True, True,  False]
 
         """
-        raise NotImplementedError
+        mask = cls.select_mask(dataset, selection)
+        mask = mask.to_dask_array().compute_chunk_sizes()
+        extra = (mask[1:] ^ mask[:-1])
+        mask[1:] |= extra
+        mask[:-1] |= extra
+        return mask
 
     @classmethod
     def groupby(cls, dataset, dimensions, container_type, group_type, **kwargs):

From ae35f9e48be55b64aea8253b5ea1f4c3947f431f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Wed, 20 Dec 2023 11:34:46 +0100
Subject: [PATCH 11/28] Add error message to logging

---
 holoviews/operation/downsample.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index a863909faf..d1bd22d39e 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -187,8 +187,8 @@ def _process(self, element, key=None):
                 )
             except NotImplementedError:
                 mask = slice(*self.p.x_range)
-            except Exception:
-                self.param.warning("Could not apply neighbor mask to downsample1d.")
+            except Exception as e:
+                self.param.warning(f"Could not apply neighbor mask to downsample1d: {e}")
                 mask = slice(*self.p.x_range)
             element = element[mask]
 

From 3ceaf73b559f8dc66ecd325210c66f0c8b263348 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Wed, 20 Dec 2023 11:55:41 +0100
Subject: [PATCH 12/28] Correct if statement in dask interface

---
 holoviews/core/data/dask.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/holoviews/core/data/dask.py b/holoviews/core/data/dask.py
index 50e1257287..9efc422ec0 100644
--- a/holoviews/core/data/dask.py
+++ b/holoviews/core/data/dask.py
@@ -154,7 +154,8 @@ def select_mask(cls, dataset, selection):
     def select(cls, dataset, selection_mask=None, **selection):
         df = dataset.data
         if selection_mask is not None:
-            if hasattr(df, "__array__"):
+            import dask.array as da
+            if isinstance(selection_mask, da.Array):
                 return df.loc[selection_mask]
             return df[selection_mask]
         selection_mask = cls.select_mask(dataset, selection)

From 7ef8c6c959a705439d98d1f4c2cd535662223547 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Wed, 20 Dec 2023 13:49:19 +0100
Subject: [PATCH 13/28] Remove xlim hack

---
 holoviews/operation/downsample.py | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index d1bd22d39e..b3a5b48ea5 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -171,7 +171,11 @@ class downsample1d(ResampleOperation1D):
     algorithm = param.Selector(default='lttb', objects=list(_ALGORITHMS))
 
     def _process(self, element, key=None):
-        self.p.x_range = self.p.x_range or element.opts.get().kwargs.get("xlim")  # hack
+        if not self.p.x_range:
+            # We don't want to send all the data to the frontend on the first pass
+            # if we have set xlims. Therefore we return the element without any data,
+            # this will render the plot and trigger a second pass with the x_range set.
+            return element[()]
         if isinstance(element, (Overlay, NdOverlay)):
             _process = partial(self._process, key=key)
             if isinstance(element, Overlay):

From 5fc5e73373ab3669dafdaa187c7ffddd83c3e1b4 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Wed, 20 Dec 2023 13:55:01 +0100
Subject: [PATCH 14/28] Nit change

---
 holoviews/core/data/dask.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/holoviews/core/data/dask.py b/holoviews/core/data/dask.py
index 9efc422ec0..ebffe3519d 100644
--- a/holoviews/core/data/dask.py
+++ b/holoviews/core/data/dask.py
@@ -177,7 +177,7 @@ def _select_mask_neighbor(cls, dataset, selection):
         """
         mask = cls.select_mask(dataset, selection)
         mask = mask.to_dask_array().compute_chunk_sizes()
-        extra = (mask[1:] ^ mask[:-1])
+        extra = mask[1:] ^ mask[:-1]
         mask[1:] |= extra
         mask[:-1] |= extra
         return mask

From 662cc9088f9f0cc3119da88db16fd5a9b118e878 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Wed, 20 Dec 2023 14:10:12 +0100
Subject: [PATCH 15/28] Move x_range check down

---
 holoviews/operation/downsample.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index b3a5b48ea5..8bcbeba490 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -171,11 +171,6 @@ class downsample1d(ResampleOperation1D):
     algorithm = param.Selector(default='lttb', objects=list(_ALGORITHMS))
 
     def _process(self, element, key=None):
-        if not self.p.x_range:
-            # We don't want to send all the data to the frontend on the first pass
-            # if we have set xlims. Therefore we return the element without any data,
-            # this will render the plot and trigger a second pass with the x_range set.
-            return element[()]
         if isinstance(element, (Overlay, NdOverlay)):
             _process = partial(self._process, key=key)
             if isinstance(element, Overlay):
@@ -195,6 +190,11 @@ def _process(self, element, key=None):
                 self.param.warning(f"Could not apply neighbor mask to downsample1d: {e}")
                 mask = slice(*self.p.x_range)
             element = element[mask]
+        else:
+            # We don't want to send all the data to the frontend on the first pass
+            # if we have set xlims. Therefore we return the element without any data,
+            # this will render the plot and trigger a second pass with the x_range set.
+            return element[()]
 
         if len(element) <= self.p.width:
             return element

From 811196614fd5914bdf65018d45311a77cf879963 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Wed, 20 Dec 2023 15:08:07 +0100
Subject: [PATCH 16/28] Send empty plot for real this time

---
 holoviews/operation/downsample.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index 8bcbeba490..952a7d6c29 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -194,7 +194,7 @@ def _process(self, element, key=None):
             # We don't want to send all the data to the frontend on the first pass
             # if we have set xlims. Therefore we return the element without any data,
             # this will render the plot and trigger a second pass with the x_range set.
-            return element[()]
+            return element.clone(data=[])
 
         if len(element) <= self.p.width:
             return element

From 3c9d2f6d15e1cfa4e16214864fa677ac7a705d6d Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Fri, 22 Dec 2023 09:54:59 +0100
Subject: [PATCH 17/28] Add viewport-xlim as workaround for now

---
 holoviews/operation/downsample.py | 9 +++++++--
 1 file changed, 7 insertions(+), 2 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index 952a7d6c29..857aec34b4 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -155,6 +155,7 @@ def _viewport(x, y, n_out):
     'lttb': _lttb,
     'nth': _nth_point,
     'viewport': _viewport,
+    'viewport-xlim': _viewport,
 }
 
 
@@ -190,10 +191,14 @@ def _process(self, element, key=None):
                 self.param.warning(f"Could not apply neighbor mask to downsample1d: {e}")
                 mask = slice(*self.p.x_range)
             element = element[mask]
-        else:
+        elif self.p.algorithm == "viewport-xlim":
             # We don't want to send all the data to the frontend on the first pass
-            # if we have set xlims. Therefore we return the element without any data,
+            # if we have set xlims. Therefore we send the element without any data,
             # this will render the plot and trigger a second pass with the x_range set.
+            # This will not work with the matplotlib backend, because it does not update
+            # the x_range after the first pass, but that is not a problem because
+            # the matplotlib backend with the viewport algorithm does not make any sense.
+            # This is not very elegant, but it works.
             return element.clone(data=[])
 
         if len(element) <= self.p.width:

From 6ba3b6f70581ac59c24d3d827692682318cd05d5 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Fri, 22 Dec 2023 10:27:36 +0100
Subject: [PATCH 18/28] Add width points to get a better approximation of the
 data in the y-direction

---
 holoviews/operation/downsample.py | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index 857aec34b4..b36c78c52e 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -198,8 +198,15 @@ def _process(self, element, key=None):
             # This will not work with the matplotlib backend, because it does not update
             # the x_range after the first pass, but that is not a problem because
             # the matplotlib backend with the viewport algorithm does not make any sense.
-            # This is not very elegant, but it works.
-            return element.clone(data=[])
+            # This is not very elegant.
+            size = element.dataset.shape[0]
+            mask1 = element.dataset.interface.select_mask(
+                element.dataset, {element.kdims[0]: slice(self.p.width // 2)},
+            )
+            mask2 = element.dataset.interface.select_mask(
+                element.dataset, {element.kdims[0]: slice(size - self.p.width // 2, size)},
+            )
+            element = element[mask1 | mask2]
 
         if len(element) <= self.p.width:
             return element

From 06436c51ab7425964e92779d67b1e449e31e04f3 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Fri, 22 Dec 2023 11:03:06 +0100
Subject: [PATCH 19/28] Add unit test

---
 holoviews/tests/core/data/base.py               | 6 ++++++
 holoviews/tests/core/data/test_ibisinterface.py | 7 +++++++
 2 files changed, 13 insertions(+)

diff --git a/holoviews/tests/core/data/base.py b/holoviews/tests/core/data/base.py
index ed8121688e..34bd776c0f 100644
--- a/holoviews/tests/core/data/base.py
+++ b/holoviews/tests/core/data/base.py
@@ -858,6 +858,12 @@ def test_dataset_transform_add_ht(self):
                              kdims=self.kdims, vdims=self.vdims+['combined'])
         self.assertEqual(transformed, expected)
 
+    def test_select_with_neighbor(self):
+        select = self.table.interface.select_mask(self.table.dataset, {"Weight": 18})
+        select_neighbor = self.table.interface._select_mask_neighbor(self.table.dataset, dict(Weight=18))
+
+        np.testing.assert_almost_equal(select, [False, True, False])
+        np.testing.assert_almost_equal(select_neighbor, [True, True, True])
 
 
 class ScalarColumnTests:
diff --git a/holoviews/tests/core/data/test_ibisinterface.py b/holoviews/tests/core/data/test_ibisinterface.py
index 3f0b4d1773..2b488ec7a6 100644
--- a/holoviews/tests/core/data/test_ibisinterface.py
+++ b/holoviews/tests/core/data/test_ibisinterface.py
@@ -256,6 +256,13 @@ def test_aggregation_operations(self):
 
             self.compare_dataset(expected, result, msg=str(agg))
 
+    def test_select_with_neighbor(self):
+        try:
+            # Not currently supported by Ibis
+            super().test_select_with_neighbor()
+        except NotImplementedError:
+            raise SkipTest("Not supported")
+
     if not IbisInterface.has_rowid():
 
         def test_dataset_iloc_slice_rows_slice_cols(self):

From 9d6adc85b7f1df9a6b50f1d97fe3d31c6723cef2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Fri, 22 Dec 2023 11:42:03 +0100
Subject: [PATCH 20/28] Add viewport options to docstring

[skip ci]
---
 holoviews/operation/downsample.py | 2 ++
 1 file changed, 2 insertions(+)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index b36c78c52e..a63f5193e9 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -167,6 +167,8 @@ class downsample1d(ResampleOperation1D):
 
         - `lttb`: Largest Triangle Three Buckets downsample algorithm
         - `nth`: Selects every n-th point.
+        - `viewport`: Selects all points in a given viewport
+        - `viewport-xlim`: Selects all points in a given viewport, when xlim is set
     """
 
     algorithm = param.Selector(default='lttb', objects=list(_ALGORITHMS))

From ee457ae7b370405c1aaec79c4ab0f86e1bb70814 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Fri, 22 Dec 2023 12:03:03 +0100
Subject: [PATCH 21/28] Update comment

[skip ci]
---
 holoviews/operation/downsample.py | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index a63f5193e9..cd495987be 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -194,12 +194,12 @@ def _process(self, element, key=None):
                 mask = slice(*self.p.x_range)
             element = element[mask]
         elif self.p.algorithm == "viewport-xlim":
-            # We don't want to send all the data to the frontend on the first pass
-            # if we have set xlims. Therefore we send the element without any data,
-            # this will render the plot and trigger a second pass with the x_range set.
-            # This will not work with the matplotlib backend, because it does not update
-            # the x_range after the first pass, but that is not a problem because
-            # the matplotlib backend with the viewport algorithm does not make any sense.
+            # We only want to send some of the data to the browser on the
+            # first pass if we have set xlim. This will render the plot and
+            # trigger a second pass with the x_range set. This will not work
+            # with the matplotlib backend because it does not update the x_range
+            # after the first pass, but that is not a problem because the matplotlib
+            # backend with the viewport algorithm does not make any sense.
             # This is not very elegant.
             size = element.dataset.shape[0]
             mask1 = element.dataset.interface.select_mask(

From 257e5fb6e276c9c0a00629005a2ca8a4ec2a5aa9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Wed, 17 Jan 2024 16:02:07 +0100
Subject: [PATCH 22/28] Only send the needed data during the initial rendering

---
 holoviews/operation/downsample.py     | 19 -------------------
 holoviews/plotting/bokeh/callbacks.py |  6 ++++++
 holoviews/plotting/bokeh/plot.py      |  3 ---
 3 files changed, 6 insertions(+), 22 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index cd495987be..269f3d92ac 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -155,7 +155,6 @@ def _viewport(x, y, n_out):
     'lttb': _lttb,
     'nth': _nth_point,
     'viewport': _viewport,
-    'viewport-xlim': _viewport,
 }
 
 
@@ -168,7 +167,6 @@ class downsample1d(ResampleOperation1D):
         - `lttb`: Largest Triangle Three Buckets downsample algorithm
         - `nth`: Selects every n-th point.
         - `viewport`: Selects all points in a given viewport
-        - `viewport-xlim`: Selects all points in a given viewport, when xlim is set
     """
 
     algorithm = param.Selector(default='lttb', objects=list(_ALGORITHMS))
@@ -193,23 +191,6 @@ def _process(self, element, key=None):
                 self.param.warning(f"Could not apply neighbor mask to downsample1d: {e}")
                 mask = slice(*self.p.x_range)
             element = element[mask]
-        elif self.p.algorithm == "viewport-xlim":
-            # We only want to send some of the data to the browser on the
-            # first pass if we have set xlim. This will render the plot and
-            # trigger a second pass with the x_range set. This will not work
-            # with the matplotlib backend because it does not update the x_range
-            # after the first pass, but that is not a problem because the matplotlib
-            # backend with the viewport algorithm does not make any sense.
-            # This is not very elegant.
-            size = element.dataset.shape[0]
-            mask1 = element.dataset.interface.select_mask(
-                element.dataset, {element.kdims[0]: slice(self.p.width // 2)},
-            )
-            mask2 = element.dataset.interface.select_mask(
-                element.dataset, {element.kdims[0]: slice(size - self.p.width // 2, size)},
-            )
-            element = element[mask1 | mask2]
-
         if len(element) <= self.p.width:
             return element
         xs, ys = (element.dimension_values(i) for i in range(2))
diff --git a/holoviews/plotting/bokeh/callbacks.py b/holoviews/plotting/bokeh/callbacks.py
index 8cf7639e38..a057c68e2c 100644
--- a/holoviews/plotting/bokeh/callbacks.py
+++ b/holoviews/plotting/bokeh/callbacks.py
@@ -645,6 +645,12 @@ class RangeXYCallback(Callback):
         'y1': 'cb_obj.y1',
     }
 
+    def initialize(self, plot_id=None):
+        super().initialize(plot_id)
+        for stream in self.streams:
+            msg = self._process_msg({})
+            stream.update(**msg)
+
     def _process_msg(self, msg):
         if self.plot.state.x_range is not self.plot.handles['x_range']:
             x_range = self.plot.handles['x_range']
diff --git a/holoviews/plotting/bokeh/plot.py b/holoviews/plotting/bokeh/plot.py
index 7e3814df76..37771afb1b 100644
--- a/holoviews/plotting/bokeh/plot.py
+++ b/holoviews/plotting/bokeh/plot.py
@@ -173,9 +173,6 @@ def _update_datasource(self, source, data):
         """
         Update datasource with data for a new frame.
         """
-        if not self.document:
-            return
-
         data = self._postprocess_data(data)
         empty = all(len(v) == 0 for v in data.values())
         if (self.streaming and self.streaming[0].data is self.current_frame.data

From aa477f467ddb4e0cd2d30c91e602925a7adcd5ef Mon Sep 17 00:00:00 2001
From: Philipp Rudiger <prudiger@anaconda.com>
Date: Wed, 24 Jan 2024 19:00:57 +0100
Subject: [PATCH 23/28] Discard change callbacks until plot is fully
 initialized

---
 holoviews/plotting/bokeh/callbacks.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/holoviews/plotting/bokeh/callbacks.py b/holoviews/plotting/bokeh/callbacks.py
index a057c68e2c..f6f07716d4 100644
--- a/holoviews/plotting/bokeh/callbacks.py
+++ b/holoviews/plotting/bokeh/callbacks.py
@@ -404,6 +404,7 @@ def set_callback(self, handle):
         if self.on_changes:
             change_handler = lambda attr, old, new: (
                 asyncio.create_task(self.on_change(attr, old, new))
+                 if self.plot.document else None
             )
             for change in self.on_changes:
                 if change in ['patching', 'streaming']:

From a44cc549794bad8c75fd70101b2736a78c17c6c8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Wed, 24 Jan 2024 20:38:22 +0100
Subject: [PATCH 24/28] Update holoviews/plotting/bokeh/callbacks.py

---
 holoviews/plotting/bokeh/callbacks.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/holoviews/plotting/bokeh/callbacks.py b/holoviews/plotting/bokeh/callbacks.py
index f6f07716d4..6a1bdd638c 100644
--- a/holoviews/plotting/bokeh/callbacks.py
+++ b/holoviews/plotting/bokeh/callbacks.py
@@ -404,7 +404,7 @@ def set_callback(self, handle):
         if self.on_changes:
             change_handler = lambda attr, old, new: (
                 asyncio.create_task(self.on_change(attr, old, new))
-                 if self.plot.document else None
+                if self.plot.document else None
             )
             for change in self.on_changes:
                 if change in ['patching', 'streaming']:

From 3ddb49c74988b41fe8cb00cfae6495f38c575a8e Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Mon, 29 Jan 2024 19:44:12 +0100
Subject: [PATCH 25/28] Update tests

---
 holoviews/tests/operation/test_downsample.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/holoviews/tests/operation/test_downsample.py b/holoviews/tests/operation/test_downsample.py
index c3057df92c..02b491e567 100644
--- a/holoviews/tests/operation/test_downsample.py
+++ b/holoviews/tests/operation/test_downsample.py
@@ -9,6 +9,8 @@
 except ImportError:
     tsdownsample = None
 
+algorithms = _ALGORITHMS.copy()
+algorithms.pop('viewport', None)  # viewport return slice(len(data)) no matter the width
 
 @pytest.mark.parametrize("plottype", ["overlay", "ndoverlay"])
 def test_downsample1d_multi(plottype):
@@ -26,7 +28,7 @@ def test_downsample1d_multi(plottype):
             assert value.size == downsample1d.width
 
 
-@pytest.mark.parametrize("algorithm", _ALGORITHMS.values(), ids=_ALGORITHMS)
+@pytest.mark.parametrize("algorithm", algorithms.values(), ids=algorithms)
 def test_downsample_algorithm(algorithm, unimport):
     unimport("tsdownsample")
     x = np.arange(1000)
@@ -37,14 +39,18 @@ def test_downsample_algorithm(algorithm, unimport):
     except NotImplementedError:
         pytest.skip("not testing tsdownsample algorithms")
     else:
+        if isinstance(result, slice):
+            result = x[result]
         assert result.size == width
 
 
 @pytest.mark.skipif(not tsdownsample, reason="tsdownsample not installed")
-@pytest.mark.parametrize("algorithm", _ALGORITHMS.values(), ids=_ALGORITHMS)
+@pytest.mark.parametrize("algorithm", algorithms.values(), ids=algorithms)
 def test_downsample_algorithm_with_tsdownsample(algorithm):
     x = np.arange(1000)
     y = np.random.rand(1000)
     width = 20
     result = algorithm(x, y, width)
+    if isinstance(result, slice):
+        result = x[result]
     assert result.size == width

From 2a64d0e3ac1372e1bbf80733d73a2f01ca5bf528 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Tue, 30 Jan 2024 10:51:38 +0100
Subject: [PATCH 26/28] Small fixes

---
 holoviews/operation/downsample.py | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index a87aef5cb1..9c78e0e051 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -157,7 +157,7 @@ def _nth_point(x, y, n_out, **kwargs):
     n_samples = len(x)
     return slice(0, n_samples, max(1, math.ceil(n_samples / n_out)))
 
-def _viewport(x, y, n_out):
+def _viewport(x, y, n_out, **kwargs):
     return slice(len(x))
 
 def _min_max(x, y, n_out, **kwargs):
@@ -211,14 +211,14 @@ class downsample1d(ResampleOperation1D):
     algorithm = param.Selector(default='lttb', objects=list(_ALGORITHMS), doc="""
         The algorithm to use for downsampling:
 
-        - `lttb`: Largest Triangle Three Buckets downsample algorithm
+        - `lttb`: Largest Triangle Three Buckets downsample algorithm.
         - `nth`: Selects every n-th point.
-        - `viewport`: Selects all points in a given viewport
+        - `viewport`: Selects all points in a given viewport.
         - `minmax`: Selects the min and max value in each bin (requires tsdownsampler).
         - `m4`: Selects the min, max, first and last value in each bin (requires tsdownsampler).
         - `minmax-lttb`: First selects n_out * minmax_ratio min and max values,
-          then further reduces these to n_out values using the
-          Largest Triangle Three Buckets algorithm. (requires tsdownsampler)""")
+                         then further reduces these to n_out values using the
+                         Largest Triangle Three Buckets algorithm (requires tsdownsampler).""")
 
     parallel = param.Boolean(default=False, doc="""
        The number of threads to use (if tsdownsampler is available).""")

From d6b654f628ec7b1d6acccf36a246e916b2da11bd Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Tue, 30 Jan 2024 10:57:46 +0100
Subject: [PATCH 27/28] Extract compute mask from _process and make it an
 options

---
 holoviews/operation/downsample.py | 36 +++++++++++++++++++++++--------
 1 file changed, 27 insertions(+), 9 deletions(-)

diff --git a/holoviews/operation/downsample.py b/holoviews/operation/downsample.py
index 9c78e0e051..9ffdd3e896 100644
--- a/holoviews/operation/downsample.py
+++ b/holoviews/operation/downsample.py
@@ -228,6 +228,10 @@ class downsample1d(ResampleOperation1D):
        values to generate with the minmax algorithm before further
        downsampling with LTTB.""")
 
+    neighbor_points = param.Boolean(default=None, doc="""
+        Whether to add the neighbor points to the range before downsampling.
+        By default this is only enabled for the viewport algorithm.""")
+
     def _process(self, element, key=None):
         if isinstance(element, (Overlay, NdOverlay)):
             _process = partial(self._process, key=key)
@@ -238,15 +242,7 @@ def _process(self, element, key=None):
             return element.clone(elements)
 
         if self.p.x_range:
-            try:
-                mask = element.dataset.interface._select_mask_neighbor(
-                    element.dataset, {element.kdims[0]: self.p.x_range}
-                )
-            except NotImplementedError:
-                mask = slice(*self.p.x_range)
-            except Exception as e:
-                self.param.warning(f"Could not apply neighbor mask to downsample1d: {e}")
-                mask = slice(*self.p.x_range)
+            mask = self._compute_mask(element)
             element = element[mask]
         if len(element) <= self.p.width:
             return element
@@ -263,3 +259,25 @@ def _process(self, element, key=None):
             kwargs['minmax_ratio'] = self.p.minmax_ratio
         samples = downsample(xs, ys, self.p.width, parallel=self.p.parallel, **kwargs)
         return element.iloc[samples]
+
+    def _compute_mask(self, element):
+        """
+        Computes the mask to apply to the element before downsampling.
+        """
+        neighbor_enabled = (
+            self.p.neighbor_points
+            if self.p.neighbor_points is not None
+            else self.p.algorithm == "viewport"
+        )
+        if not neighbor_enabled:
+            return slice(*self.p.x_range)
+        try:
+            mask = element.dataset.interface._select_mask_neighbor(
+                element.dataset, {element.kdims[0]: self.p.x_range}
+            )
+        except NotImplementedError:
+            mask = slice(*self.p.x_range)
+        except Exception as e:
+            self.param.warning(f"Could not apply neighbor mask to downsample1d: {e}")
+            mask = slice(*self.p.x_range)
+        return mask

From 0e9ca5d8bd9cb2cd4b1bc9a7df5fb499e5c9678f Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Simon=20H=C3=B8xbro=20Hansen?= <simon.hansen@me.com>
Date: Tue, 30 Jan 2024 11:46:23 +0100
Subject: [PATCH 28/28] Ignore cuDF test

---
 holoviews/tests/core/data/test_cudfinterface.py | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/holoviews/tests/core/data/test_cudfinterface.py b/holoviews/tests/core/data/test_cudfinterface.py
index cdb6c19014..87cb469190 100644
--- a/holoviews/tests/core/data/test_cudfinterface.py
+++ b/holoviews/tests/core/data/test_cudfinterface.py
@@ -104,3 +104,10 @@ def test_dataset_groupby_second_dim(self):
 
     def test_dataset_aggregate_string_types_size(self):
         raise SkipTest("cuDF does not support variance aggregation")
+
+    def test_select_with_neighbor(self):
+        try:
+            # Not currently supported by CuDF
+            super().test_select_with_neighbor()
+        except NotImplementedError:
+            raise SkipTest("Not supported")