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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?


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