Preferred Python idiom for handling non-existing dictionary keys and why?

[Dave Benjamin]

In article <jOWcnYmbcsYclhqiXTWJig at comcast.com>, Terry Reedy wrote:
> 
> "Quentin Crain" <czrpb at yahoo.com> wrote in message
> news:mailman.1065807808.957.python-list at python.org...
>>
>> Which is perferred and why?
> 
> Neither.  For me, both are superceded by
> 
> d={}
> for (k,v) in somedata():
>     d[k] = d.get(k, []).append(v)

Not quite... append returns None, so you'll need to write that as two
separate statements, ie.:

d[k] = d.get(k, [])
d[k].append(v)

Or, just:

d.setdefault(k, []).append(v)

-- 
.:[ dave benjamin (ramenboy) -:- www.ramenfest.com -:- www.3dex.com ]:.
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