COBAYA: Contour level outside plotted ranges

[Ali Rida Khalife]

Hello!
I'm running the Quick example in Cobaya, and trying to produce a triangular plot with getdist, when I do that I get the following:
WARNING:root:Parameters are 100% correlated: a, derived_a
/path/to/cobaya/getdist/mcsamples.py:1777: RuntimeWarning: invalid value encountered in divide
corrected = (bins2D[ix] * A + xP * Ax + yP * Ay) / denom
Traceback (most recent call last):
File "/path/to/Plot.py", line 16, in <module>
g.triangle_plot(samples, filled=True)
File "/path/to/cobaya/getdist/plots.py", line 2476, in triangle_plot
self.plot_2d(roots, param_pair=pair, do_xlabel=i2 == plot_col - 1, do_ylabel=i == 0,
File "/path/to/cobaya/getdist/plots.py", line 1686, in plot_2d
res = self.add_2d_contours(root, param_pair[0], param_pair[1], line_offset + i, of=len(roots), ax=ax,
File "/path/to/cobaya/getdist/plots.py", line 1057, in add_2d_contours
density = self.sample_analyser.get_density_grid(root, param1, param2,
File "/path/to/cobaya/getdist/plots.py", line 613, in get_density_grid
density = samples.get2DDensityGridData(param1.name, param2.name, num_plot_contours=conts, meanlikes=likes)
File "/path/to/cobaya/getdist/mcsamples.py", line 1812, in get2DDensityGridData
density.contours = density.getContourLevels(contours)
File "/path/to/cobaya/getdist/densities.py", line 127, in getContourLevels
return getContourLevels(self.P, contours)
File "/path/to/cobaya/getdist/densities.py", line 51, in getContourLevels
raise DensitiesError("Contour level outside plotted ranges")
getdist.densities.DensitiesError: Contour level outside plotted ranges
I'm attaching the python script I'm using to produce the plot.
Could someone please help me solve this issue?

[Antony Lewis]

Looks like your a and derived_a parameters are the same.

[Ali Rida Khalife]

Thanks Antony for the reply! I'm using the exact same input file as given in the Quick example https://cobaya.readthedocs.io/en/latest/example.html in cobaya. So they are already the same in the example?

[Antony Lewis]

The example doesn't plot a and derived_a at the same time though.