Plotting a dataset with negative errors is not allowed

[juliuskarliczek]

Describe the bug
I am not sure, whether this problem was addressed in the document from Paul yesterday and i did not see an open issue with this. Feel free to link, if one exists.

When loading one of the example datasets from src/sas/example_data/coordinate_data/sphere_R=0_2025.vtk,
quick plotting this dataset throws an error, because it dataset contains negative values in the errors
(This is a bug, that was also reported to me by a beta test user here at ILL yesterday )
To Reproduce
Steps to reproduce the behavior:

1. Start sasview
2. Load data sphere_R=0_2025.vtk into the data explorer
3. Use quick plotting option "create new" on the bottom of the data explorer
4. See error

Screenshots

SasView version (please complete the following information):

• release_6.0.0 branch

Operating system (please complete the following information):

• OS: win10

[krzywon]

The error thrown is from matplotlib. I would argue this is expected behavior. Negative errors have no physical meaning and are unplottable.

As a side note, the data file loaded in your example is not SAS data. It is multi-column x,y,z coordinate data, not I vs Q data. The ASCII reader can and will read any multi-column data file, but that doesn't mean the data is valid and analyzable. Coordinate data are meant to be opened by the generic scattering calculator, not via the data explorer.

[juliuskarliczek]

Thanks for clearing that up, i did not know that. The user mentioned, that this error did not occur in 5.0.6