On Mon, Jun 10, 2013 at 10:56 PM, Philipp Kraus <philipp.kraus@flashpixx.de> wrote:

On 2013-06-10 21:44:21 +0200, sguazt said:





On Mon, Jun 10, 2013 at 9:13 PM, Philipp Kraus <philipp.kraus@flashpixx.de> wrote:

On 2013-06-10 20:58:40 +0200, sguazt said:




On Mon, Jun 10, 2013 at 4:22 PM, Philipp Kraus <philipp.kraus@flashpixx.de> wrote:

Hello,


I would like to create a box plot and use the static calls of the boost. Median / average etc works well, but I need also the 25% & 75% quantil of my data, I'm using a

boost::accumulators::accumulator_set for calculating statistical data. Can I / How can I use this for the quantil calculation or should I do this myself?


Thanks


Phil


Hi,


Have you tried p_square_quantile from boost::accumulator?


http://www.boost.org/doc/libs/1_53_0/doc/html/accumulators/user_s_guide.html#accumulators.user_s_guide.the_statistical_accumulators_library.p_square_quantile 


It uses a well-known algorithm to incrementally compute quantile estimation.


Great thanks, I don't see this section. But another question: I have defined my accumulator like

               typedef boost::accumulators::accumulator_set<double, boost::accumulators::stats<

                   boost::accumulators::tag::count,

                   boost::accumulators::tag::sum,

                   boost::accumulators::tag::median,

                   boost::accumulators::tag::mean,

                   boost::accumulators::tag::variance,

                   boost::accumulators::tag::min,

                   boost::accumulators::tag::max,

                   boost::accumulators::tag::p_square_quantile

               > > Accumulator;


Within the example the quantil value is set in the Ctor of the accumulator. In my case I need two quantiles

0.25 & 0.75 so I need two p_square_quantile parts in my accu, so how I can add the two quantils and how I

can set it to the values?



You can use the extended_p_square_quantile ;)


See the example here:


http://www.boost.org/doc/libs/1_53_0/doc/html/accumulators/user_s_guide.html#accumulators.user_s_guide.the_statistical_accumulators_library.extended_p_square_quantile 


Thanks, but I can not create a working example and I can not compile the example code on the page.

I have set up my typedef to:

                typedef boost::accumulators::accumulator_set<double, boost::accumulators::stats< 

                    boost::accumulators::tag::count,

                    boost::accumulators::tag::sum,

                    boost::accumulators::tag::median, 

                    boost::accumulators::tag::mean, 

                    boost::accumulators::tag::variance,

                    boost::accumulators::tag::min,

                    boost::accumulators::tag::max,

                    boost::accumulators::tag::extended_p_square

                > > Accumulator;

and try to create the ctor call with


boost::array<double> probs = {0.25, 0.75};

x = Accumulator( boost::accumulators::tag::extended_p_square::probabilities = probs );


I get the error:

error: wrong number of template arguments (1, should be 2)

/Boost/1.53.0/include/boost/fusion/support/tag_of.hpp:24: error: provided for 'template<class T, long unsigned int N> class boost::array'

error: invalid type in declaration before '=' token

error: scalar object 'probs' requires one element in initializer


I don't see my mistake at the moment. Thanks a lot for your help, this calls seems to be the correct parameter for creating the whisker on a box plot.


I think the error refers to boost::array which needs an additional parameter representing the (fixed) sized of the array.

Also, you can replace tag::median with the calculation of 0.50th quantile:

using namespace boost::accumulators;

typedef accumulator_set<double,
                        stats<tag::count,
                              tag::sum,
                              tag::mean,
                              tag::extended_p_square_quantile> > accumulator_t;


int main()
{
    boost::array<double,3> probs = {0.25, 0.50, 0.75};

    accumulator_t acc(extended_p_square_probabilities = probs);
}

I got compilation errors if I add tag::variance, tag::min and tag::max.
Unfortunately, I don't know how to solve it. Sorry

In the meanwhile, you can always keep two separate accumulators.

Best,

-- Marco