Closed
Description
Bug report
Bug summary
When using scatter, with the c= argument, I accidentally used an (n,2) array, instead of what I intended (an n-length vector). As expected, this did raise an error, however the error is misleading, and doesn't help much with debugging.
Code for reproduction
import matplotlib.pyplot as plt
import numpy as np
x = np.linspace(0,1,10)
col = np.random.random(size=(10,2))
plt.scatter(x,x,c=col) # woops! should have been plt.scatter(x,x, c=col[:,0]).Actual outcome
Traceback (most recent call last):
File "/home/steven/miniconda3/envs/py21cmmc_fg/lib/python3.7/site-packages/matplotlib/colors.py", line 158, in to_rgba
rgba = _colors_full_map.cache[c, alpha]
TypeError: unhashable type: 'numpy.ndarray'
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "/home/steven/miniconda3/envs/py21cmmc_fg/lib/python3.7/site-packages/matplotlib/axes/_axes.py", line 4210, in scatter
colors = mcolors.to_rgba_array(c)
File "/home/steven/miniconda3/envs/py21cmmc_fg/lib/python3.7/site-packages/matplotlib/colors.py", line 259, in to_rgba_array
result[i] = to_rgba(cc, alpha)
File "/home/steven/miniconda3/envs/py21cmmc_fg/lib/python3.7/site-packages/matplotlib/colors.py", line 160, in to_rgba
rgba = _to_rgba_no_colorcycle(c, alpha)
File "/home/steven/miniconda3/envs/py21cmmc_fg/lib/python3.7/site-packages/matplotlib/colors.py", line 215, in _to_rgba_no_colorcycle
raise ValueError("RGBA sequence should have length 3 or 4")
ValueError: RGBA sequence should have length 3 or 4
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "instrumental_tests.py", line 218, in <module>
test_imaging_single_source()
File "instrumental_tests.py", line 156, in test_imaging_single_source
test_imaging(SingleSource())
File "instrumental_tests.py", line 91, in test_imaging
c=np.real(ctx.get("visibilities")))
File "/home/steven/miniconda3/envs/py21cmmc_fg/lib/python3.7/site-packages/matplotlib/__init__.py", line 1785, in inner
return func(ax, *args, **kwargs)
File "/home/steven/miniconda3/envs/py21cmmc_fg/lib/python3.7/site-packages/matplotlib/axes/_axes.py", line 4223, in scatter
.format(nc=n_elem, xs=x.size, ys=y.size)
ValueError: 'c' argument has 10 elements, which is not acceptable for use with 'x' with size 10, 'y' with size 10.
Expected outcome
Expected exception would have been something like either ValueError: 'c' argument has 20 elements, which is not acceptable for use with 'x' with size 10, 'y' with size 10., or even better: ValueError: 'c' argument has shape (10,2), which is not acceptable for use with 'x' with size 10, 'y' with size 10.
Matplotlib version
v3.0.0