Bug summary

scatter plot can handle categorical data and list of lists separately, but cannot handle then both that seems inconsistent. Looks at the examples

Code for reproduction

import matplotlib.pyplot as plt

# runs
plt.scatter([1,2,3], ["a", "b", "a"])
plt.show()

# runs
plt.scatter([[1, 0],[ 0, 1]], 
           [[1, 2], [2, 3]])
plt.show()

# fails
plt.scatter([[1, 0],[ 0, 1]], 
           [["a", "b"], ["b", "a"]])
plt.show()

Actual outcome

ValueError Traceback (most recent call last)
Cell In[51], line 11
8 plt.show()
10 # fails
---> 11 plt.scatter([[1, 0],[ 0, 1]],
12 [["a", "b"], ["b", "a"]])
13 plt.show()

File ~\anaconda3\lib\site-packages\matplotlib\pyplot.py:2862, in scatter(x, y, s, c, marker, cmap, norm, vmin, vmax, alpha, linewidths, edgecolors, plotnonfinite, data, **kwargs)
2857 @_copy_docstring_and_deprecators(Axes.scatter)
2858 def scatter(
2859 x, y, s=None, c=None, marker=None, cmap=None, norm=None,
2860 vmin=None, vmax=None, alpha=None, linewidths=None, *,
2861 edgecolors=None, plotnonfinite=False, data=None, **kwargs):
-> 2862 __ret = gca().scatter(
2863 x, y, s=s, c=c, marker=marker, cmap=cmap, norm=norm,
2864 vmin=vmin, vmax=vmax, alpha=alpha, linewidths=linewidths,
2865 edgecolors=edgecolors, plotnonfinite=plotnonfinite,
2866 **({"data": data} if data is not None else {}), **kwargs)
2867 sci(__ret)
2868 return __ret

File ~\anaconda3\lib\site-packages\matplotlib_init_.py:1459, in _preprocess_data..inner(ax, data, *args, **kwargs)
1456 @functools.wraps(func)
1457 def inner(ax, *args, data=None, **kwargs):
1458 if data is None:
-> 1459 return func(ax, *map(sanitize_sequence, args), **kwargs)
1461 bound = new_sig.bind(ax, *args, **kwargs)
1462 auto_label = (bound.arguments.get(label_namer)
1463 or bound.kwargs.get(label_namer))

File ~\anaconda3\lib\site-packages\matplotlib\axes_axes.py:4673, in Axes.scatter(self, x, y, s, c, marker, cmap, norm, vmin, vmax, alpha, linewidths, edgecolors, plotnonfinite, **kwargs)
4667 linewidths = [
4668 lw if lw is not None else mpl.rcParams['lines.linewidth']
4669 for lw in linewidths]
4671 offsets = np.ma.column_stack([x, y])
-> 4673 collection = mcoll.PathCollection(
4674 (path,), scales,
4675 facecolors=colors,
4676 edgecolors=edgecolors,
4677 linewidths=linewidths,
4678 offsets=offsets,
4679 offset_transform=kwargs.pop('transform', self.transData),
4680 alpha=alpha,
4681 )
4682 collection.set_transform(mtransforms.IdentityTransform())
4683 if colors is None:

File ~\anaconda3\lib\site-packages\matplotlib\collections.py:994, in PathCollection.init(self, paths, sizes, **kwargs)
980 def init(self, paths, sizes=None, **kwargs):
981 """
982 Parameters
983 ----------
(...)
991 Forwarded to .Collection.
992 """
--> 994 super().init(**kwargs)
995 self.set_paths(paths)
996 self.set_sizes(sizes)

File ~\anaconda3\lib\site-packages\matplotlib_api\deprecation.py:454, in make_keyword_only..wrapper(*args, **kwargs)
448 if len(args) > name_idx:
449 warn_deprecated(
450 since, message="Passing the %(name)s %(obj_type)s "
451 "positionally is deprecated since Matplotlib %(since)s; the "
452 "parameter will become keyword-only %(removal)s.",
453 name=name, obj_type=f"parameter of {func.name}()")
--> 454 return func(*args, **kwargs)

File ~\anaconda3\lib\site-packages\matplotlib\collections.py:192, in Collection.init(self, edgecolors, facecolors, linewidths, linestyles, capstyle, joinstyle, antialiaseds, offsets, offset_transform, norm, cmap, pickradius, hatch, urls, zorder, **kwargs)
189 self._joinstyle = None
191 if offsets is not None:
--> 192 offsets = np.asanyarray(offsets, float)
193 # Broadcast (2,) -> (1, 2) but nothing else.
194 if offsets.shape == (2,):

ValueError: could not convert string to float: 'a'

Expected outcome

it should provide plot with categorical data on y-axis

Additional information

No response

Operating system

Windows

Matplotlib Version

3.7.1

Matplotlib Backend

module://matplotlib_inline.backend_inline

Python version

3.10.12

Jupyter version

6.5.3

Installation

conda