Error when first element of a plotted series is NA #1021
Description
Consider the following example:
import pandas as pd
(
pd.DataFrame({'x': [0,1,2,3], 'y': pd.Series([0,pd.NA,2,3], dtype="Int64")})
>>
ggplot(aes(x='x', y='y')) + geom_line()
)
This correctly produces a plot (after removing the missing value). However, if the NA in y is moved to the front:
import pandas as pd
(
pd.DataFrame({'x': [0,1,2,3], 'y': pd.Series([pd.NA,1,2,3], dtype="Int64")})
>>
ggplot(aes(x='x', y='y')) + geom_line()
)
we get (with plotnine 0.15.2 and pandas 2.3.3) the following:
---------------------------------------------------------------------------
ValueError Traceback (most recent call last)
File [~/micromamba/envs/ds435/lib/python3.14/site-packages/IPython/core/formatters.py:1036](http://localhost:8888/home/peter/micromamba/envs/ds435/lib/python3.14/site-packages/IPython/core/formatters.py#line=1035), in MimeBundleFormatter.__call__(self, obj, include, exclude)
1033 method = get_real_method(obj, self.print_method)
1035 if method is not None:
-> 1036 return method(include=include, exclude=exclude)
1037 return None
1038 else:
File [~/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/ggplot.py:172](http://localhost:8888/home/peter/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/ggplot.py#line=171), in ggplot._repr_mimebundle_(self, include, exclude)
169 self.theme = self.theme.to_retina()
171 buf = BytesIO()
--> 172 self.save(buf, "png" if format == "retina" else format, verbose=False)
173 figure_size_px = self.theme._figure_size_px
174 return get_mimebundle(buf.getvalue(), format, figure_size_px)
File [~/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/ggplot.py:681](http://localhost:8888/home/peter/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/ggplot.py#line=680), in ggplot.save(self, filename, format, path, width, height, units, dpi, limitsize, verbose, **kwargs)
632 def save(
633 self,
634 filename: Optional[str | Path | BytesIO] = None,
(...) 643 **kwargs: Any,
644 ):
645 """
646 Save a ggplot object as an image file
647
(...) 679 Additional arguments to pass to matplotlib `savefig()`.
680 """
--> 681 sv = self.save_helper(
682 filename=filename,
683 format=format,
684 path=path,
685 width=width,
686 height=height,
687 units=units,
688 dpi=dpi,
689 limitsize=limitsize,
690 verbose=verbose,
691 **kwargs,
692 )
694 with plot_context(self).rc_context:
695 sv.figure.savefig(**sv.kwargs)
File [~/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/ggplot.py:629](http://localhost:8888/home/peter/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/ggplot.py#line=628), in ggplot.save_helper(self, filename, format, path, width, height, units, dpi, limitsize, verbose, **kwargs)
626 if dpi is not None:
627 self.theme = self.theme + theme(dpi=dpi)
--> 629 figure = self.draw(show=False)
630 return mpl_save_view(figure, fig_kwargs)
File [~/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/ggplot.py:306](http://localhost:8888/home/peter/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/ggplot.py#line=305), in ggplot.draw(self, show)
304 with plot_context(self, show=show):
305 figure = self._setup()
--> 306 self._build()
308 # setup
309 self.axs = self.facet.setup(self)
File [~/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/ggplot.py:390](http://localhost:8888/home/peter/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/ggplot.py#line=389), in ggplot._build(self)
387 # Map and train positions so that statistics have access
388 # to ranges and all positions are numeric
389 layout.train_position(layers, scales)
--> 390 layout.map_position(layers)
392 # Apply and map statistics
393 layers.compute_statistic(layout)
File [~/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/facets/layout.py:136](http://localhost:8888/home/peter/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/facets/layout.py#line=135), in Layout.map_position(self, layers)
132 y_vars = list(
133 set(self.panel_scales_y[0].aesthetics) & set(data.columns)
134 )
135 SCALE_Y = _layout["SCALE_Y"].iloc[match_id].tolist()
--> 136 self.panel_scales_y.map(data, y_vars, SCALE_Y)
File [~/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/scales/scales.py:178](http://localhost:8888/home/peter/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/scales/scales.py#line=177), in Scales.map(self, data, vars, idx)
176 for i, sc in enumerate(self, start=1):
177 bool_idx = i == idx
--> 178 results = sc.map(data.loc[bool_idx, col])
179 if use_df:
180 discrete_data.loc[bool_idx, col] = results
File [~/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/scales/scale_xy.py:205](http://localhost:8888/home/peter/micromamba/envs/ds435/lib/python3.14/site-packages/plotnine/scales/scale_xy.py#line=204), in scale_position_continuous.map(self, x, limits)
203 if limits is None:
204 limits = self.final_limits
--> 205 scaled = self.oob(x, limits) # type: ignore
206 scaled[pd.isna(scaled)] = self.na_value
207 return scaled
File [~/micromamba/envs/ds435/lib/python3.14/site-packages/mizani/bounds.py:351](http://localhost:8888/home/peter/micromamba/envs/ds435/lib/python3.14/site-packages/mizani/bounds.py#line=350), in censor(x, range, only_finite)
348 if not len(x):
349 return res
--> 351 null = get_null_value(x)
353 if only_finite:
354 try:
File [~/micromamba/envs/ds435/lib/python3.14/site-packages/mizani/utils.py:359](http://localhost:8888/home/peter/micromamba/envs/ds435/lib/python3.14/site-packages/mizani/utils.py#line=358), in get_null_value(x)
357 return type(x0)("NaT")
358 else:
--> 359 raise ValueError(
360 "Cannot get a null value for type: {}".format(type(x[0]))
361 )
ValueError: Cannot get a null value for type: <class 'pandas._libs.missing.NAType'>
The error does not occur if we don't specify the nullable dtype "Int64".