A legend entry is generated for samples that do not have distributions.
df_dist = pd.DataFrame([[0.0003, 0.12, pf.distribution.NormalDistribution(mean=200, sigma=50)],
[0.0004, 0.12, pf.distribution.NormalDistribution(mean=340, sigma=50)],
[0.0002, 0.7, pf.distribution.NormalDistribution(mean=340, sigma=20)],
[0.00012, 1.1, pf.distribution.NormalDistribution(mean=90, sigma=30)],
[0.00004, 2.3, pf.distribution.NormalDistribution(mean=310, sigma=50)]],
index=['ID1', 'ID2', 'ID3', 'ID4', 'ID5'],
columns=['conc', 'elevation', 'distribution'])
stn.conc_obs = pf.observation.SedimentConcentrationObservations(data=df_dist, connection=connection)
stn.conc_obs._data.at['ID5', 'distribution'] = np.nan
stn.conc_obs2.show_distributions(cumulative=True, savestr='temp/dists_cum.png', log_x=True)