RuntimeError in kde plot when data includes NaNs

[lukashergt]

When the data contains NaNs kde_contour_plot_2d raises a RuntimeError. This should not happen for cases where the corresponding logL is -inf and weight is 0. In such cases these entries should be simply ignored.

NaNs can appear for derived parameters which never got calculated when the sampling parameters fell into an excluded region (logL=-inf and weight=0) of parameter space.

MWE

data: unilog_r.log

data = pandas.read_csv("unilog_r.log", sep='\t')
ns = NestedSamples(data=data[['n_s', 'r', 'logr']], logL=data.logL, logL_birth=data.logL_birth, w=data.weight)
ns.n_s[:10] = np.nan
assert np.all(ns.weight[:10] == 0)
fig = plt.figure(figsize=(5, 5))
fig, axes = make_2d_axes(['n_s', 'r', 'logr'], fig=fig)
ns.plot_2d(axes)
axes.iloc[-1, 0].legend(bbox_to_anchor=(len(axes), len(axes)), loc='upper left');

The error message:

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
<ipython-input-160-14d6415b9f86> in <module>
      5 fig = plt.figure(figsize=(5, 5))
      6 fig, axes = make_2d_axes(['n_s', 'r', 'logr'], fig=fig)
----> 7 ns.plot_2d(axes)
      8 axes.iloc[-1, 0].legend(bbox_to_anchor=(len(axes), len(axes)), loc='upper left');

~/.virtualenvs/py38env/lib/python3.8/site-packages/anesthetic/samples.py in plot_2d(self, axes, *args, **kwargs)
    352                     plot_type = types.get(pos, None)
    353                     lkwargs = local_kwargs.get(pos, {})
--> 354                     self.plot(ax_, x, y, plot_type=plot_type, *args, **lkwargs)
    355 
    356         return fig, axes

~/.virtualenvs/py38env/lib/python3.8/site-packages/anesthetic/samples.py in plot(self, ax, paramname_x, paramname_y, *args, **kwargs)
    192                     x = self[paramname_x]
    193                     y = self[paramname_y]
--> 194                     return kde_contour_plot_2d(ax, x, y, weights=self.weight,
    195                                                xmin=xmin, xmax=xmax,
    196                                                ymin=ymin, ymax=ymax,

~/.virtualenvs/py38env/lib/python3.8/site-packages/anesthetic/plot.py in kde_contour_plot_2d(ax, data_x, data_y, *args, **kwargs)
    528 
    529     cov = np.cov(data_x, data_y, aweights=weights)
--> 530     tri, w = triangular_sample_compression_2d(data_x, data_y, cov,
    531                                               weights, ncompress)
    532     kde = gaussian_kde([tri.x, tri.y], weights=w)

~/.virtualenvs/py38env/lib/python3.8/site-packages/anesthetic/utils.py in triangular_sample_compression_2d(x, y, cov, w, n)
    300 
    301     # Generate triangulation
--> 302     tri = scaled_triangulation(x[i], y[i], cov)
    303 
    304     # For each point find corresponding triangles

~/.virtualenvs/py38env/lib/python3.8/site-packages/anesthetic/utils.py in scaled_triangulation(x, y, cov)
    257     Linv = np.linalg.inv(L)
    258     x_, y_ = Linv.dot([x, y])
--> 259     tri = Triangulation(x_, y_)
    260     return Triangulation(x, y, tri.triangles)
    261 

~/.virtualenvs/py38env/lib/python3.8/site-packages/matplotlib/tri/triangulation.py in __init__(self, x, y, triangles, mask)
     52             # No triangulation specified, so use matplotlib._qhull to obtain
     53             # Delaunay triangulation.
---> 54             self.triangles, self._neighbors = _qhull.delaunay(x, y)
     55             self.is_delaunay = True
     56         else:

RuntimeError: Error in qhull Delaunay triangulation calculation: input inconsistency (exitcode=1); use python verbose option (-v) to see original qhull error.