Sum models break the docs

[mmaelicke]

Hey @rhugonnet,

The docs are not compiling anymore and I finally found the time to have a look at that. To me it seems like the the standard plotting routine has an issue, when calling the Variogram.fitted_model through Variogram.transform. It is one of the V.plot(); statements in docs/userguide/variogram.rst. It started failing after we implemented the sum of models. I can't really tell which of the plot statements causes the error, but we added to that file, so I suspect it is one of the newly added plotting of sum of models. Here is the traceback of building the docs locally:

>>>-------------------------------------------------------------------------
Exception in /Users/mirko/Library/CloudStorage/Dropbox/python/scikit-gstat/docs/userguide/variogram.rst at block ending on line None
Specify :okexcept: as an option in the ipython:: block to suppress this message
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[129], line 1
----> 1 V.plot();

File ~/Library/CloudStorage/Dropbox/python/scikit-gstat/skgstat/Variogram.py:2966, in Variogram.plot(self, axes, grid, show, hist)
   2963 used_backend = plotting.backend()
   2965 if used_backend == 'matplotlib':
-> 2966     return plotting.matplotlib_variogram_plot(
   2967         self,
   2968         axes=axes,
   2969         grid=grid,
   2970         show=show,
   2971         hist=hist
   2972     )
   2973 elif used_backend == 'plotly':
   2974     return plotting.plotly_variogram_plot(
   2975         self,
   2976         fig=axes,
   (...)
   2979         hist=hist
   2980     )

File ~/Library/CloudStorage/Dropbox/python/scikit-gstat/skgstat/plotting/variogram_plot.py:38, in matplotlib_variogram_plot(variogram, axes, grid, show, hist)
     30 def matplotlib_variogram_plot(
     31     variogram,
     32     axes=None,
   (...)
     36 ):
     37     # get the plotting data
---> 38     x, y, _bins, _exp = __calculate_plot_data(variogram)
     40     # do the plotting
     41     if axes is None:

File ~/Library/CloudStorage/Dropbox/python/scikit-gstat/skgstat/plotting/variogram_plot.py:18, in __calculate_plot_data(variogram)
     15 x = np.linspace(0, np.nanmax(_bins), 100)
     17 # apply the model
---> 18 y = variogram.transform(x)
     20 # handle the relative experimental variogram
     21 if variogram.normalized:

File ~/Library/CloudStorage/Dropbox/python/scikit-gstat/skgstat/Variogram.py:1817, in Variogram.transform(self, x)
   1814     self.fit(force=True)
   1816 # return the result
-> 1817 return self.fitted_model(x)

File <string>:1, in <lambda>(x)

File ~/Library/CloudStorage/Dropbox/python/scikit-gstat/skgstat/models.py:15, in variogram.<locals>.wrapper(*args, **kwargs)
     13     new_args = args[1:]
     14     mapping = map(lambda h: func(h, *new_args, **kwargs), args[0])
---> 15     return np.fromiter(mapping, dtype=float)
     16 else:
     17     return func(*args, **kwargs)

File ~/Library/CloudStorage/Dropbox/python/scikit-gstat/skgstat/models.py:14, in variogram.<locals>.wrapper.<locals>.<lambda>(h)
     12 if hasattr(args[0], '__iter__'):
     13     new_args = args[1:]
---> 14     mapping = map(lambda h: func(h, *new_args, **kwargs), args[0])
     15     return np.fromiter(mapping, dtype=float)
     16 else:

File ~/Library/CloudStorage/Dropbox/python/scikit-gstat/skgstat/Variogram.py:1070, in Variogram._build_sum_models.<locals>.sum_models(h, *args)
   1068 @models.variogram
   1069 def sum_models(h, *args):
-> 1070     return sum(list_models[i](h, *args[args_slices[i]]) for i in range(len(list_models)))

File ~/Library/CloudStorage/Dropbox/python/scikit-gstat/skgstat/Variogram.py:1070, in <genexpr>(.0)
   1068 @models.variogram
   1069 def sum_models(h, *args):
-> 1070     return sum(list_models[i](h, *args[args_slices[i]]) for i in range(len(list_models)))

TypeError: spherical() missing 1 required positional argument: 'c0'

<<<-------------------------------------------------------------------------

@rhugonnet I am a bit lost here. Do you have any idea, what exactly is going wrong here?