chore: opposite categories

[aleene]

What

Adding opposite characteristics to categories, as discussed in the data quality meeting. Based on the list on https://wiki.openfoodfacts.org/Data_quality_missions.

Some on the list are not included as these are better designated by the characteristic exclusive (can not be combined with another category)..

[CharlesNepote]

Great!

To go further, could you explain deeper the "exclusive" characteristic? What I understand is that an "exclusive" category means that the product can't have another category than itself and its parents.
Eg. Plant-based foods and beverages > Plant-based foods | Condiments > Spices > Peppers > White Peppers

But could you also provide an example of a category that is NOT exclusive?

Regarding to the list here, could you make two lists: one containing the opposites and one containing the exclusives?

[aleene]

We could add tests:

• the opposite category name should exist as a category in order to prevent spelling errors
• the opposite category should also have an opposite category that refers back

[aleene]

The final categories (leaves/end points) should be exclusive. A product can not belong to multiple leaves, for instance a meat can not be a fish nor a black pepper. A leaf category can have multiple parents, for instance skimmed milk can belong to pasteurised milks and homogenised milks.
Opposite products define the relation between leaves based on some characteristic, i.e. pasteurised milks versus unpasteurised milks. Opposite products are a special case of exclusivity and have only one common direct parent
Opposite products are also a special case of Set-related leaves. Set leaves do not have just two possible values, but more, for instance: skimmed, semi-skimmed, whole milks; or short, medium or long grain rice.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[stephanegigandet]

The opposite of "Beverages" would be "Food" I think, not "meals". Of course that would mean putting most parent categories under "Food"

[stephanegigandet]

I added a comment for beverages vs meals. Otherwise it looks good to me. I think we could try it, and add some data quality warnings based on it, to see what product it flags, and then we could adjust.