Decide how to handle dictionary values

[kalekundert]

I ran into an unhelpful error message today. Here's a MWE. It has an error, which is that the well name is specified twice. This ultimately has the effect of making the well value seem to be a dictionary:

[well.A1]
A1.foo = 'bar'

When I try to visualize this layout, I get the following stack trace:

Traceback (most recent call last):
  File "/home/kale/.pyenv/versions/3.10.0/bin/wellmap", line 8, in <module>
    sys.exit(main())
  File "/home/kale/research/software/projects/wellmap/wellmap/gui.py", line 342, in main
    app = AppWindow(toml_path, color)
  File "/home/kale/research/software/projects/wellmap/wellmap/gui.py", line 119, in __init__
    self.reload_layout()
  File "/home/kale/research/software/projects/wellmap/wellmap/gui.py", line 262, in reload_layout
    fig = wellmap.plot.plot_layout(df, attr, cmap)
  File "/home/kale/research/software/projects/wellmap/wellmap/plot.py", line 91, in plot_layout
    fig, axes, dims = setup_axes(df, plates, attrs)
  File "/home/kale/research/software/projects/wellmap/wellmap/plot.py", line 210, in setup_axes
    dims = Dimensions(df)
  File "/home/kale/research/software/projects/wellmap/wellmap/plot.py", line 317, in __init__
    self.num_values = df.nunique()
  File "/home/kale/.pyenv/versions/3.10.0/lib/python3.10/site-packages/pandas/core/frame.py", line 10143, in nunique
    return self.apply(Series.nunique, axis=axis, dropna=dropna)
  File "/home/kale/.pyenv/versions/3.10.0/lib/python3.10/site-packages/pandas/core/frame.py", line 8833, in apply
    return op.apply().__finalize__(self, method="apply")
  File "/home/kale/.pyenv/versions/3.10.0/lib/python3.10/site-packages/pandas/core/apply.py", line 727, in apply
    return self.apply_standard()
  File "/home/kale/.pyenv/versions/3.10.0/lib/python3.10/site-packages/pandas/core/apply.py", line 851, in apply_standard
    results, res_index = self.apply_series_generator()
  File "/home/kale/.pyenv/versions/3.10.0/lib/python3.10/site-packages/pandas/core/apply.py", line 867, in apply_series_generator
    results[i] = self.f(v)
  File "/home/kale/.pyenv/versions/3.10.0/lib/python3.10/site-packages/pandas/core/apply.py", line 138, in f
    return func(x, *args, **kwargs)
  File "/home/kale/.pyenv/versions/3.10.0/lib/python3.10/site-packages/pandas/core/base.py", line 1027, in nunique
    uniqs = self.unique()
  File "/home/kale/.pyenv/versions/3.10.0/lib/python3.10/site-packages/pandas/core/series.py", line 2088, in unique
    return super().unique()
  File "/home/kale/.pyenv/versions/3.10.0/lib/python3.10/site-packages/pandas/core/base.py", line 989, in unique
    result = unique1d(values)
  File "/home/kale/.pyenv/versions/3.10.0/lib/python3.10/site-packages/pandas/core/algorithms.py", line 440, in unique
    uniques = table.unique(values)
  File "pandas/_libs/hashtable_class_helper.pxi", line 5361, in pandas._libs.hashtable.PyObjectHashTable.unique
  File "pandas/_libs/hashtable_class_helper.pxi", line 5310, in pandas._libs.hashtable.PyObjectHashTable._unique
TypeError: unhashable type: 'dict'

In short, the plotting code tries to figure out the number of unique values, and pandas chokes on the non-hashable type. The data loads without error.

Initially I wanted to raise an error in this case, but there's no way to do that without forbidding dictionary values altogether. So instead, I should probably make the plotting code robust against such inputs.