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