How to get a directory list sorted by date?

[Peter Otten]

Tim Chase wrote:

> On 2016-05-15 11:46, Peter Otten wrote:
>> def sorted_dir(folder):
>>     def getmtime(name):
>>         path = os.path.join(folder, name)
>>         return os.path.getmtime(path)
>> 
>>     return sorted(os.listdir(folder), key=getmtime, reverse=True)
>> 
>> The same idea will work with pathlib and os.scandir():
>> 
>> def _getmtime(entry):
>>     return entry.stat().st_mtime
>> 
>> def sd_sorted_dir(folder):
>>     return sorted(os.scandir(folder), key=_getmtime, reverse=True)
> 
> unless sorted() returns a lazy sorter, you lose most of the advantages
> of scandir() being lazy since you have to read the entire directory
> list into memory to sort it.

I mentioned it because it avoids the duplicate stat call of the older 
approach which is rather inelegant.

Taking another look at the OP's problem I think sorting could be entirely 
avoided. Instead have the memory card remember when its data was last 
archived. Pseudo-code:

try:
    cut_off = load_cut_off(memory_card)
    pics = (pic for pic in memory_card if gettime(pic) > cut_off)
except:
    pics = memory_card
    
for pic in pics:
    copy_to_archive(pic)

save_cut_off(now(), memory_card)

As long as computer and camera time are in sync...