Closed
Description
Bug report
Bug summary
Using a scatter plot with a single point at. But using a single number for the "c" keyword gave an slightly unhelpful error about a TypeError from mcolors.to_rgba_array. A cmap is used to map the number given but this is omitted here as the Error is still reproduced.
Code for reproduction
import maptlotlib.pyplot as plt
plt.scatter([0], [1], c=0.5)Actual outcome
---------------------------------------------------------------------------
TypeError Traceback (most recent call last)
<ipython-input-16-a8c544fd7de9> in <module>()
----> 1 plt.scatter([0], [1], c=0.5)
~/anaconda3/lib/python3.6/site-packages/matplotlib/pyplot.py in scatter(x, y, s, c, marker, cmap, norm, vmin, vmax, alpha, linewidths, verts, edgecolors, hold, data, **kwargs)
3376 vmin=vmin, vmax=vmax, alpha=alpha,
3377 linewidths=linewidths, verts=verts,
-> 3378 edgecolors=edgecolors, data=data, **kwargs)
3379 finally:
3380 ax._hold = washold
~/anaconda3/lib/python3.6/site-packages/matplotlib/__init__.py in inner(ax, *args, **kwargs)
1715 warnings.warn(msg % (label_namer, func.__name__),
1716 RuntimeWarning, stacklevel=2)
-> 1717 return func(ax, *args, **kwargs)
1718 pre_doc = inner.__doc__
1719 if pre_doc is None:
~/anaconda3/lib/python3.6/site-packages/matplotlib/axes/_axes.py in scatter(self, x, y, s, c, marker, cmap, norm, vmin, vmax, alpha, linewidths, verts, edgecolors, **kwargs)
3981 try:
3982 # must be acceptable as PathCollection facecolors
-> 3983 colors = mcolors.to_rgba_array(c)
3984 except ValueError:
3985 # c not acceptable as PathCollection facecolor
~/anaconda3/lib/python3.6/site-packages/matplotlib/colors.py in to_rgba_array(c, alpha)
229 pass
230 # Convert one at a time.
--> 231 result = np.empty((len(c), 4), float)
232 for i, cc in enumerate(c):
233 result[i] = to_rgba(cc, alpha)
TypeError: object of type 'int' has no len()
Expected outcome
Have a useful message from an except TypeError: from the failing colors = mcolors.to_rgba_array(c) call in line 3983 much like the ValueError except, would probably do it.
Helpfully indicating that c must be the correct type (color, sequence, or sequence of color).
Note:
With x, y, and c all as single numbers the scatter plot call runs without any errors raised,
e.g. plt.scatter(0, 1, c=0.5)