EDIT: the link here now points to a revised version of the file that uses a stamp rather than a rule for reasons described in the thread “Annotated co-occurrence example code”.
Building off @PaulWalters’ demo “Open Code Example with Export.tbx”, I offer “OpenCode Example with co-occurence.tbx” (zipped TBX) with two extra agents. One uses the unique sorted string** of all code values for a given note and finds occurrence. this means shorter strings are detected within longer ones as both use the same sort order in construction.
The second does what I think Derek’s after. It finds all co-occurrence of value pairs (where AB is considered the same as BA) regardless of the number of $OpenCode values per note; notes with zero or a single value are ignored as no pair exists.
I’m sure there are edge cases and I’ve not even tried to extend to triples or quartets, etc. I hope this puts us all back on the same page again. I’ve only tested o the example in the TBX I used, I suppsect with 100 discrete $Opencode values performance might be less snappy!
** I fixed one error in the original TBX as when casting $OpenCode to $CodeCollector, .isort wants to be chained before .format() so it is the sorted list that gets formatted rather than a single formatted string (that can’t be sorted!).