Brightway2 writing the imported database - python-3.x

Question

I created several excel inventory files using the eco invent exchanges.
To run my LCA I successfully imported the database with 0 unlinked exchanges using:
imp = bw.ExcelImporter("Inventory_fuelcell.xlsx")
imp.apply_strategies()
imp.match_database("ecoinvent 3.6 cutoff", fields=('name','unit','location'))
imp.match_database("biosphere3", fields=('name','unit'))
imp.match_database(fields=('name', 'unit', 'location'))
imp.statistics()
But when I run imp.write_database()
I get the following error:
Writing activities to SQLite3 database:
0% [######## ] 100% | ETA: 00:00:00
---------------------------------------------------------------------------
InvalidExchange Traceback (most recent call last)
<ipython-input-41-1daab0bbe8d8> in <module>
----> 1 imp.write_database()
/opt/anaconda3/envs/Masterarbeit/lib/python3.7/site-packages/bw2io/importers/excel.py in write_database(self, **kwargs)
257 """Same as base ``write_database`` method, but ``activate_parameters`` is True by default."""
258 kwargs['activate_parameters'] = kwargs.get('activate_parameters', True)
--> 259 super(ExcelImporter, self).write_database(**kwargs)
260
261 def get_activity(self, sn, ws):
/opt/anaconda3/envs/Masterarbeit/lib/python3.7/site-packages/bw2io/importers/base_lci.py in write_database(self, data, delete_existing, backend, activate_parameters, **kwargs)
238
239 existing.update(data)
--> 240 db.write(existing)
241
242 if activate_parameters:
/opt/anaconda3/envs/Masterarbeit/lib/python3.7/site-packages/bw2data/project.py in writable_project(wrapped, instance, args, kwargs)
354 if projects.read_only:
355 raise ReadOnlyProject(READ_ONLY_PROJECT)
--> 356 return wrapped(*args, **kwargs)
/opt/anaconda3/envs/Masterarbeit/lib/python3.7/site-packages/bw2data/backends/peewee/database.py in write(self, data, process)
258 if data:
259 try:
--> 260 self._efficient_write_many_data(data)
261 except:
262 # Purge all data from database, then reraise
/opt/anaconda3/envs/Masterarbeit/lib/python3.7/site-packages/bw2data/backends/peewee/database.py in _efficient_write_many_data(self, data, indices)
203 for index, (key, ds) in enumerate(data.items()):
204 exchanges, activities = self._efficient_write_dataset(
--> 205 index, key, ds, exchanges, activities
206 )
207
/opt/anaconda3/envs/Masterarbeit/lib/python3.7/site-packages/bw2data/backends/peewee/database.py in _efficient_write_dataset(self, index, key, ds, exchanges, activities)
154 for exchange in ds.get('exchanges', []):
155 if 'input' not in exchange or 'amount' not in exchange:
--> 156 raise InvalidExchange
157 if 'type' not in exchange:
158 raise UntypedExchange
InvalidExchange:
I never had this problem before.
Is there a way to figure out where the invalid exchange is?
But even with the error if I look for databases it still shows up.
So it seems like the database was in fact imported.
Can anybody help me what could be wrong?

Answer 1

If we look through the error traceback, we can see the line raising the error:
154 for exchange in ds.get('exchanges', []):
155 if 'input' not in exchange or 'amount' not in exchange:
--> 156 raise InvalidExchange
This means that at least one exchange doesn't have an input or and amount. As all your exchanges are linked, they all have input values, so the amount must be missing. This could be due to a typo in the column field, or off by one errors, etc.
To find it, you could try:
for ds in imp.data:
for exc in ds['exchanges']:
if 'amount' not in exc:
print("Missing `amount` in exc:")
print("\t", exc)
print("Dataset", ds['name'], ds['location'])
elif 'input' not in exc:
# check just to make sure
print("Missing `input` in exc:")
print("\t", exc)
print("Dataset", ds['name'], ds['location'])