Re: [Boost-users] [accumulators] question

Subject: Re: [Boost-users] [accumulators] question
From: Eric Niebler (eric_at_[hidden])
Date: 2010-02-15 02:33:08

On 2/15/2010 1:14 PM, Neal Becker wrote:
> Eric Niebler wrote:
>
>> On 2/14/2010 9:13 AM, Neal Becker wrote:
>>> If I have:
>>>
>>>     typedef accumulator_set<el_t,stats<tag::mean>   >   accum_t;
>>>
>>> Is there a way to get the count of the number of samples?
>>
>> You need to add a dependency on the count feature:
>>
>>     accumulator_set<el_t, stats<tag::mean, tag::count>  >
>>
>> Now you can get the count of samples using the count extractor.
>
> Thanks, but before I saw this response, I already tried simply doing
> count(accum), without adding the count tag, since it seemed to be part of
> the examples shown here: http://www.boost.org/doc
> /libs/1_37_0/doc/html/accumulators/user_s_guide.html#
> accumulators.user_s_guide.the_statistical_accumulators_library.mean
>
> and it seems to work (compiles, at least).

The mean accumulator depends on the count accumulator, so yes, this 
works. But it's better to state up-front which features you plan to 
extract later, as only those extractors are guaranteed to work.

-- 
Eric Niebler
BoostPro Computing
http://www.boostpro.com