Re: [boost] accumulators::histogram

From: Matthias Troyer (troyer_at_[hidden])
Date: 2008-01-30 13:00:19

On 30 Jan 2008, at 08:26, Neal Becker wrote:

> Eric Niebler wrote:
>
>> Neal Becker wrote:
>>> I see accumulators::density is almost what I want.  I need a  
>>> histogram,
>>> but
>>> it want to specify in advance the number of bins and the bin  
>>> size.  This
>>> is really a simplified accumulators::density.
>>>
>>> I think it would be good to add this to accumulators::density.
>>
>> Do these help?
>>
>> tag::density::cache_size
>>   Number of first samples used to determine min and max.
>>
>> tag::density::num_bins
>>  Number of bins (two additional bins collect under-
>>  and overflow samples).
>>
>> They are named parameters that you can specify to an  
>> accumulator_set's
>> constructor.
>>
>> accumulator_set<double, features<tag::density> > acc(
>>     tag::density::cache_size = 10
>>     tag::density::num_bins = 20
>> );
>>
>> HTH,
>>
> I don't think that helps.  How can I specify apriori the number of  
> bins and
> the min and max?  AFAICT, the above would let me do this by forcing  
> in some
> fake data, that has the effect of filling the cache and thus setting
> num_bins, min, max, but is has the side effect of causing that data to
> effect the histogram - which is not what I need.
>
> Unless I misunderstand, we need another (simpler) class "histogram"  
> that
> implements just this simpler behavior.  Perhaps density could be  
> build on
> top of it?

It would indeed be nice to be able to explicitly specify the min and  
max for the bins and I guess that should not be too hard to do. Eric,  
what do you think?

Matthias