Re: [Python-ideas] Allow a group by operation for dict comprehension

I think you accidentally swapped variables there: student_school_list vs student_by_school

Oops, yeah. That’s what I get for whipping out a message before catching a bus. (And on a phone now) But maybe you could wrap the defaultdict constructor around a generator expression that transforms the list first. That would get the keys right. Though still not call append for you. So maybe a solution is an accumulator special case of defaultdict — it uses a list be default and appends by default. Almost like counter... -CHB