Exclude 'None' from list comprehension of dicts

[Loris Bennett]

Antoon Pardon <antoon.pardon at vub.be> writes:

> Op 4/08/2022 om 13:51 schreef Loris Bennett:
>> Hi,
>>
>> I am constructing a list of dictionaries via the following list
>> comprehension:
>>
>>    data = [get_job_efficiency_dict(job_id) for job_id in job_ids]
>>
>> However,
>>
>>    get_job_efficiency_dict(job_id)
>>
>> uses 'subprocess.Popen' to run an external program and this can fail.
>> In this case, the dict should just be omitted from 'data'.
>>
>> I can have 'get_job_efficiency_dict' return 'None' and then run
>>
>>    filtered_data = list(filter(None, data))
>>
>> but is there a more elegant way?
>
> Just wondering, why don't you return an empty dictionary in case of a failure?
> In that case your list will be all dictionaries and empty ones will be processed
> fast enough.

When the list of dictionaries is processed, I would have to check each
element to see if it is empty.  That strikes me as being less efficient
than filtering out the empty dictionaries in one go, although obviously
one would need to benchmark that.

Cheers,

Loris


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