excel database import error in brightway2

Question

screenshot of an exchange causing problemI'm desperately attempting to import my Excel spreadsheet into my project in Brightway2, but I first encountered an error due to unique unlinked exchanges. This issue stems from having multiple product activities. To address this, I added a "reference product" column to differentiate my activities, which are meant to be linked to the ecoinvent 3.9.1 cutoff database. Then, I adjusted my importing strategies by adding reference product as follows:

imp = bw.ExcelImporter("my_database")
imp.apply_strategies()
imp.match_database("ecoinvent 3.9.1 cutoff", fields=('name','unit','location', 'reference product'))
#imp.match_database(fields=('name', 'unit', 'location', 'reference product'))
imp.statistics()

What am I overlooking here? Do I also need to specify a reference product for those activities that have no relation to ecoinvent? such as biosphere, and to those that I created?

Below, you can find the complete type error message:

Cell In[193], line 5
      3 imp.match_database("ecoinvent 3.9.1 cutoff", fields=('name','unit','location', 'reference product'))
      4 #imp.match_database(fields=('name', 'unit', 'location', 'reference product'))
----> 5 imp.statistics()

File ~/opt/.../base_lci.py:69, in LCIImporter.statistics(self, print_stats)
     67         for exc in (e for e in ds.get("exchanges", []) if not e.get("input")):
     68             unique_unlinked[exc.get("type")].add(activity_hash(exc))
---> 69     unique_unlinked = sorted(
     70         [(k, len(v)) for k, v in list(unique_unlinked.items())]
     71     )
     73     print(
     74         (
     75             u"{} datasets\n{} exchanges\n{} unlinked exchanges\n  "
   (...)
     82         ).format(num_datasets, num_exchanges, num_unlinked)
     83     )
     84 return num_datasets, num_exchanges, num_unlinked

TypeError: '<' not supported between instances of 'NoneType' and 'str'

I tried various import strategies to handle this issue. But I couldn't import my database.

Answer 1

The error says TypeError: '<' not supported between instances of 'NoneType' and 'str'. I suspect is because you are using as matching field "reference product" which is only defined for some activities (so it is a None for the case reference product field and a string in other cases).