Boxplot errors when `dodge=True` without `hue`

[Asif-Iqbal-Bhatti]

Hello,

I want to report a bug when using the latest version of Seaborn. I checked with 0.12.2 there was no error.The bug is:
File "/mnt/c/Users//Desktop/Gent_presentation_2023/1_Effect_of_Ti_addition/2-formation_energy/all_Tix_analysis/./boxplot.py", line 287, in
statplot_cols()
File "/mnt/c/Users//Desktop/Gent_presentation_2023/1_Effect_of_Ti_addition/2-formation_energy/all_Tix_analysis/./boxplot.py", line 59, in statplot_cols
pp = sns.boxplot(
File "/home//miniconda3/lib/python3.10/site-packages/seaborn/categorical.py", line 1619, in boxplot
p.plot_boxes(
File "/home//miniconda3/lib/python3.10/site-packages/seaborn/categorical.py", line 637, in plot_boxes
self._dodge(sub_vars, data)
File "/home/*****/miniconda3/lib/python3.10/site-packages/seaborn/categorical.py", line 391, in _dodge
hue_idx = self._hue_map.levels.index(keys["hue"])
KeyError: 'hue'

Can you check why is that?

[mwaskom]

I cannot help without a reproducible example.

[Asif-Iqbal-Bhatti]

Okay i will provide the test case in few moments

[Asif-Iqbal-Bhatti]

all_Tix_analysis.zip

I have uploaded the zip file which contains the code and the file which you can run on your machine to reproduce the error.

[mwaskom]

Please provide the code here and ideally adapt to one of the example datasets.

[mwaskom]

The contributing guidelines contain a list of what must be included to make a bug report actionable for maintainers: https://github.com/mwaskom/seaborn/blob/master/.github/CONTRIBUTING.md#reporting-bugs

[thuiop]

Didn't try it but I'm pretty sure the issue here is that you set dodge to True without providing a hue parameter.

[Asif-Iqbal-Bhatti]

In previous version 0.12 i did not provide hue and the dodge was set to True and it works but with 0.13 it did not.

[thuiop]

Indeed, as mentioned in the doc dodge should a value of auto to get the same behaviour. I don't really see why you pass the dodge parameter explicitely here anyway since you do not use hue.

[mwaskom]

Thanks @thuiop that suggests a reprex:

sns.boxplot(tips, x="tip", y="day", dodge=True)

---------------------------------------------------------------------------
AttributeError                            Traceback (most recent call last)
Cell In [87], line 1
----> 1 sns.boxplot(tips, x="tip", y="day", dodge=True)

File ~/code/seaborn/seaborn/categorical.py:1617, in boxplot(data, x, y, hue, order, hue_order, orient, color, palette, saturation, fill, dodge, width, gap, whis, linecolor, linewidth, fliersize, hue_norm, native_scale, log_scale, formatter, legend, ax, **kwargs)
   1610 color = _default_color(
   1611     ax.fill_between, hue, color,
   1612     {k: v for k, v in kwargs.items() if k in ["c", "color", "fc", "facecolor"]},
   1613     saturation=saturation,
   1614 )
   1615 linecolor = p._complement_color(linecolor, color, p._hue_map)
-> 1617 p.plot_boxes(
   1618     width=width,
   1619     dodge=dodge,
   1620     gap=gap,
   1621     fill=fill,
   1622     whis=whis,
   1623     color=color,
   1624     linecolor=linecolor,
   1625     linewidth=linewidth,
   1626     fliersize=fliersize,
   1627     plot_kws=kwargs,
   1628 )
   1630 p._add_axis_labels(ax)
   1631 p._adjust_cat_axis(ax, axis=p.orient)

File ~/code/seaborn/seaborn/categorical.py:635, in _CategoricalPlotter.plot_boxes(self, width, dodge, gap, fill, whis, color, linecolor, linewidth, fliersize, plot_kws)
    633 data = pd.DataFrame({self.orient: positions, "width": orig_width})
    634 if dodge:
--> 635     self._dodge(sub_vars, data)
    636 if gap:
    637     data["width"] *= 1 - gap

File ~/code/seaborn/seaborn/categorical.py:391, in _CategoricalPlotter._dodge(self, keys, data)
    389 def _dodge(self, keys, data):
    390     """Apply a dodge transform to coordinates in place."""
--> 391     hue_idx = self._hue_map.levels.index(keys["hue"])
    392     n = len(self._hue_map.levels)
    393     data["width"] /= n

AttributeError: 'NoneType' object has no attribute 'index'

Which looks similar (if not identical) to the reported traceback.

However as noted, dodge=True in v0.12 would have simply been ignored, so this is easy to work around.

[abdulwaheedsoudagar]

This issue is seen in boxenplot and violinplot, Is fix required for this?

sns.boxenplot(tips, x="tip", y="day",dodge=True)
sns.violinplot(tips, x="tip", y="day",dodge=True)

[mwaskom]

The dodge operation is undefined when you haven’t assigned a hue variable. There should probably be a fix to handle this more gracefully, but the existing bug is not preventing you from doing anything.