Append a new value to dict
Marc 'BlackJack' Rintsch
bj_666 at gmx.net
Wed Oct 22 17:12:57 EDT 2008
On Wed, 22 Oct 2008 10:12:56 -0700, bearophileHUGS wrote:
> Frank Niemeyer:
>> There's simply no
>> way to increment a non-existent value - not without performing some
>> obscure implict behind-the-scenes stuff.
>
> Like importing and using a defaultdict(int).
>
>
>> > So you
>> > either have to use a workaround:
>>
>> > >>> try:
>> > ... counter['B'] += 1
>> > ... except KeyError:
>> > ... counter['B'] = 1
>>
>> Or you could simply use
>>
>> if counter.has_key('B'):
>> counter['B'] += 1
>> else:
>> counter['B'] = 1
>
> Both those are slow. Better to use:
>
> if 'B' in counter:
> counter['B'] += 1
> else:
> counter['B'] = 1
>
> Or with a defaultdict:
>
> counter = defauldict(int)
> counter['B'] += 1
Or:
counter['B'] = counter.get('B', 0) + 1
Ciao,
Marc 'BlackJack' Rintsch
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