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

Chris Barker chris.barker at noaa.gov
Thu Jun 28 19:33:26 EDT 2018


On Thu, Jun 28, 2018 at 4:23 PM, Greg Ewing <greg.ewing at canterbury.ac.nz>
wrote:

> Nicolas Rolin wrote:
>
>>     student_by_school = {group_by(school): student for school, student in
>> student_school_list}
>>
>
> In the spirit of making the target expression look like
> a template for the generated elements,
>
>    {school: [student...] for school, student in student_school_list}


hmm -- this seems a bit non-general -- would this only work for a list?
maybe you would want a set, or???

so could be get a defaultdict comprehension with something like:

{ school: (default_factory=list, student) for school, student in
student_school_list }

But I can't think of an reasonable syntax to make that work.

-CHB









>
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> Greg
>
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