I’m not sure if this would be useful, but you can transform periodic data such as yours ….
and extend it along a single line ….
using the ‘unwrap360’ column property …
Then you could fit all the data for a single category along one line, to get the slope. You would have to have the data for a single item in one column, which you could do from a larger data set using a mask column.
Might not be what you are after but wanted to show you an example.