Step plot not working with resample_when #1716
Description
ALL software version info
Software Version Info: short
hvplot 0.12.2
python 3.12.12
marimo 0.19.6
firefox
linux
Software Version Info: full
Package Version
------------------ -----------
anyio 4.12.1
bleach 6.3.0
bokeh 3.8.2
certifi 2026.1.4
charset-normalizer 3.4.4
click 8.3.1
colorcet 3.1.0
contourpy 1.3.3
docutils 0.22.4
h11 0.16.0
holoviews 1.22.1
hvplot 0.12.2
idna 3.11
itsdangerous 2.2.0
jedi 0.19.2
jinja2 3.1.6
linkify-it-py 2.0.3
loro 1.10.3
marimo 0.19.6
markdown 3.10.1
markdown-it-py 4.0.0
markupsafe 3.0.3
mdit-py-plugins 0.5.0
mdurl 0.1.2
msgspec 0.20.0
narwhals 2.15.0
numpy 2.4.1
packaging 26.0
pandas 3.0.0
panel 1.8.6
param 2.3.1
parso 0.8.5
pillow 12.1.0
psutil 7.2.1
pyarrow 23.0.0
pygments 2.19.2
pymdown-extensions 10.20.1
python-dateutil 2.9.0.post0
pyviz-comms 3.0.6
pyyaml 6.0.3
requests 2.32.5
six 1.17.0
starlette 0.52.1
tomlkit 0.14.0
tornado 6.5.4
tqdm 4.67.1
typing-extensions 4.15.0
uc-micro-py 1.0.3
urllib3 2.6.3
uvicorn 0.40.0
webencodings 0.5.1
websockets 16.0
xyzservices 2025.11.0
Description of expected behavior and the observed behavior
Thank you very much for this excellent library!
I am trying to plot a large time series with hvplot. Therefore, I have to use downsampling. I was very happy to find the "resample_when" option, which was just what I needed.
Line plots work well. However, problems arise when I try to use step plots.
Complete, minimal, self-contained example code that reproduces the issue
import hvplot.pandas # noqa
import pandas as pd
df = pd.read_parquet("https://datasets.holoviz.org/sensor/v1/data.parq")
# works fine
df.hvplot.line(
x="time",
y="value",
downsample=True,
resample_when=1_000,
)
# also works
df.hvplot.step(
x="time",
y="value",
where="post",
downsample=True,
)
# error
df.hvplot.step(
x="time",
y="value",
where="post",
downsample=True,
resample_when=1_000,
)Stack traceback and/or browser JavaScript console output
ValueError: negative dimensions are not allowed
Traceback (most recent call last):
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/marimo/_output/formatters/holoviews_formatters.py", line 44, in _show_chart
return from_panel(plot)._mime_()
^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/marimo/_plugins/ui/_impl/from_panel.py", line 285, in __init__
ref, docs_json, render_json = render_component(self.obj)
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/marimo/_plugins/ui/_impl/from_panel.py", line 164, in render_component
root = obj._render_model(doc, comm)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/panel/viewable.py", line 768, in _render_model
model = self.get_root(doc, comm)
^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/panel/layout/base.py", line 329, in get_root
root = super().get_root(doc, comm, preprocess)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/panel/viewable.py", line 698, in get_root
root = self._get_model(doc, comm=comm)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/panel/layout/base.py", line 313, in _get_model
objects, _ = self._get_objects(model, [], doc, root, comm)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/panel/layout/base.py", line 295, in _get_objects
child = pane._get_model(doc, root, model, comm)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/panel/pane/holoviews.py", line 487, in _get_model
plot = self._render(doc, comm, root)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/panel/pane/holoviews.py", line 581, in _render
return renderer.get_plot(self.object, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/bokeh/renderer.py", line 70, in get_plot
plot = super().get_plot(obj, doc, renderer, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/renderer.py", line 239, in get_plot
plot.update(init_key)
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/plot.py", line 958, in update
return self.initialize_plot()
^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/bokeh/element.py", line 3474, in initialize_plot
child = subplot.initialize_plot(ranges, plot, plots)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/bokeh/element.py", line 2220, in initialize_plot
self._init_glyphs(plot, element, ranges, source)
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/bokeh/element.py", line 2120, in _init_glyphs
data, mapping, style = self.get_data(element, ranges, style)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/bokeh/chart.py", line 466, in get_data
element = interpolate_curve(element, interpolation=self.interpolation)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/param/parameterized.py", line 5948, in __new__
return inst.__call__(*args,**params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/operation.py", line 218, in __call__
return element.apply(self, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/accessors.py", line 43, in pipelined_call
result = __call__(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/accessors.py", line 200, in __call__
new_obj = apply_function(self._obj, **inner_kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/operation.py", line 212, in __call__
return self._apply(element)
^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/operation.py", line 141, in _apply
ret = self._process(element, key)
^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/operation/element.py", line 1142, in _process
return element.map(self._process_layer, Element)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/data/__init__.py", line 204, in pipelined_fn
result = method_fn(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/data/__init__.py", line 1316, in map
return super().map(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/dimension.py", line 761, in map
return map_fn(self) if applies else self
^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/operation/element.py", line 1136, in _process_layer
xs, dvals = INTERPOLATE_FUNCS[self.p.interpolation](x, dvals)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/operation/element.py", line 1110, in pts_to_poststep
steps = np.zeros(2 * len(x) - 1)
^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: negative dimensions are not allowed
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/marimo/_output/formatting.py", line 237, in try_format
mimetype, data = formatter(obj)
^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/marimo/_output/formatters/holoviews_formatters.py", line 47, in _show_chart
backend_output = hv.render(plot)
^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/util/__init__.py", line 892, in render
return renderer_obj.get_plot_state(obj)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/renderer.py", line 273, in get_plot_state
obj = self_or_cls.get_plot(obj=obj, renderer=renderer, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/bokeh/renderer.py", line 70, in get_plot
plot = super().get_plot(obj, doc, renderer, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/renderer.py", line 239, in get_plot
plot.update(init_key)
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/plot.py", line 958, in update
return self.initialize_plot()
^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/bokeh/element.py", line 3474, in initialize_plot
child = subplot.initialize_plot(ranges, plot, plots)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/bokeh/element.py", line 2220, in initialize_plot
self._init_glyphs(plot, element, ranges, source)
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/bokeh/element.py", line 2120, in _init_glyphs
data, mapping, style = self.get_data(element, ranges, style)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/plotting/bokeh/chart.py", line 466, in get_data
element = interpolate_curve(element, interpolation=self.interpolation)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/param/parameterized.py", line 5948, in __new__
return inst.__call__(*args,**params)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/operation.py", line 218, in __call__
return element.apply(self, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/accessors.py", line 43, in pipelined_call
result = __call__(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/accessors.py", line 200, in __call__
new_obj = apply_function(self._obj, **inner_kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/operation.py", line 212, in __call__
return self._apply(element)
^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/operation.py", line 141, in _apply
ret = self._process(element, key)
^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/operation/element.py", line 1142, in _process
return element.map(self._process_layer, Element)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/data/__init__.py", line 204, in pipelined_fn
result = method_fn(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/data/__init__.py", line 1316, in map
return super().map(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/core/dimension.py", line 761, in map
return map_fn(self) if applies else self
^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/operation/element.py", line 1136, in _process_layer
xs, dvals = INTERPOLATE_FUNCS[self.p.interpolation](x, dvals)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "/home/ar/Work/hvplot_test/.venv/lib/python3.12/site-packages/holoviews/operation/element.py", line 1110, in pts_to_poststep
steps = np.zeros(2 * len(x) - 1)
^^^^^^^^^^^^^^^^^^^^^^^^
ValueError: negative dimensions are not allowed