[Python-ideas] collections.Counter multiplication

[David Mertz]

Well... I actually *did* implement it a few notes up-thread, it's not
merely simple, but actual.  If you really want, you can privately
substitute my:

   class MyCounter(Counter): ...

with:

   class Counter(Counter): ...

Of course, I don't *recommend* doing that. :-)


On Wed, May 29, 2013 at 6:47 PM, Andrew Barnert <abarnert at yahoo.com> wrote:

> Given how simple this would be to implement, I think the obvious way
> forward is to write an implementation, put it on PyPI, and give it time to
> see if it gets any traction. If enough people use it, it can be easily
> added to the stdlib later.
>
> (IIRC, there's a project named something like more-collections that has
> OrderedSet, OrderedDefaultDict, etc., so you could submit this new class as
> a patch to that project instead of creating a new one, but that doesn't
> make too much difference.)
>
> If you don't know how to write the implementation yourself, just ask and
> someone will write it for you.
>
> Sent from a random iPhone
>
> On May 29, 2013, at 13:17, James K <jamylak at gmail.com> wrote:
>
> It should work like this
>
>     >>> from collections import Counter
>     >>> Counter({'a': 1, 'b': 2}) * 2 # scalar
>     Counter({'b': 4, 'a': 2})
>     >>> Counter({'a': 1, 'b': 2}) * Counter({'c': 1, 'b': 2}) # multiplies
> matching keys
>     Counter({'b': 4})
>
>
> This is intuitive behavior and therefore should be added. I am unsure
> about division as dividing by a non-existing key would be a division by 0,
> although division by a scalar is straightforward.
>
> On Thu, May 30, 2013 at 12:29 AM, Ned Batchelder <ned at nedbatchelder.com>wrote:
>
>>  On 5/29/2013 1:27 AM, James K wrote:
>>
>> Can we add a multiplication feature to collections.Counter, I don't see
>> why not.
>>
>>
>> James, welcome to the list.  To get an idea accepted, you have to do a
>> few things:
>>
>> 1) Explain the idea fully.  I don't understand what "a multiplication
>> feature" would do.
>> 2) Explain why the idea is useful to enough people that it should be
>> added to the standard library.
>>
>> These two criteria are not easy to meet.  Sometimes an idea seems
>> popular, but it turns out that different people want it to behave
>> differently, or differently at different times (see the discussion about an
>> itertools.chunked feature).  Sometimes an idea is straightforward enough to
>> describe, but is useful to too few people to justify adding it to the
>> standard library.
>>
>> Discussing these things doesn't often result in a change to Python, but
>> does often lead to useful discussion.
>>
>> --Ned.
>>
>>
>>
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