Skip Array data when constructing VTKData

[williamjsdavis]

Regarding issue #63, when reading data from a vtk/pvtk file, the current read implementation only work if all elements in the PointData/CellData section are of type DataArray. In some use cases, string data is stored in these sections as Array type, (e.g., as label for visualization projects, link). These elements have the form:

Currently, if there is a single Array element in the PointData/CellData section, reading data will fail due to an assertion breach in the get_data_section method:

ReadVTK.jl/src/ReadVTK.jl

Line 425 in c914447

@assert LightXML.name(xml_element) == "DataArray"

In the new implementation I present in this pull request, XML elements that are not DataArray type are skipped over in get_data_section, but error later when one attempts to index the VTKData object with a key that references non-numeric data:

ReadVTK.jl/src/ReadVTK.jl

Line 530 in c914447

function Base.getindex(data::VTKData, name)

This new logic allows for the reading of numeric data from files with both numeric and non-numeric contents.

I have also expanded existing tests to:

1. Add string data to a generated .vti file,
2. Add string data to a generated .pvti file,
3. Test for expected KeyErrors when attempting to read the string data for the .vti file, and
4. Test for expected KeyErrors when attempting to read the string data for the .pvti file

And the fact that the existing tests for reading cell/point data pass as they previously were doing indicates that numeric data can still be correctly read from .vti and .pvti files.

Feedback is appreciated!

[ranocha]

Thanks! This looks quite good to me. Would you like to add your name to the list of authors in https://github.com/JuliaVTK/ReadVTK.jl?tab=readme-ov-file#authors?

[williamjsdavis]

Yes please! I'd be very happy to continue contributing! Please add me as:

William Davis (Terra AI, USA)

[ranocha]

Could you please do that in this PR?

[williamjsdavis]

Ah understood! I've added it to the PR!

[ranocha]

Thanks