Re: [boost] [accumulator][minmax_element] Perfomance comparsion different min max algorithm

Subject: Re: [boost] [accumulator][minmax_element] Perfomance comparsion different min max algorithm
From: Hansi (hansipet_at_[hidden])
Date: 2009-02-16 13:25:43

Eric Niebler schrieb:

> 
> Did you turn on compiler optimizations? If not, the results are 
> meaningless. If you did, please post the full source code. What you 
> posted was incomplete.

sorry..yes I have turned on compiler optimization.

#include <algorithm>
#include <boost/accumulators/accumulators.hpp>
#include <boost/accumulators/statistics.hpp>
#include <boost/algorithm/minmax_element.hpp>
#include <boost/array.hpp>
#include <boost\chrono\chrono.hpp>

using namespace boost;
using namespace boost::chrono;
using namespace std;

typedef array<int,10000000> dataarray;

dataarray data;

int _tmain(int argc, _TCHAR* argv[])
{
        high_resolution_clock::time_point start = high_resolution_clock::now();
        high_resolution_clock::time_point stop = high_resolution_clock::now();

        for(unsigned int i = 0; i< data.size();i++)
        {
                data[i] = i;
        }

        start = high_resolution_clock::now();
        dataarray::iterator resmin = std::min_element(data.begin(),data.end());
        dataarray::iterator resmax = std::max_element(data.begin(),data.end());
        stop = high_resolution_clock::now();
        cout<<"min_element,max_element:"<<duration_cast<milliseconds>(stop-start).count()<<endl; 

        cout<<"minVal="<<*resmin<<",maxVal="<<*resmax<<endl;

        boost::accumulators::accumulator_set<int, 
boost::accumulators::features<boost::accumulators::tag::min,boost::accumulators::tag::max>> 
acc;

        start = high_resolution_clock::now();
        acc = std::for_each(data.begin(),data.end(),acc);
        stop = high_resolution_clock::now();
        int minVal = boost::accumulators::extract_result< 
boost::accumulators::tag::min >(acc);
        int maxVal = boost::accumulators::extract_result< 
boost::accumulators::tag::max >(acc);
        cout<<"min_max: 
accumulator:"<<duration_cast<milliseconds>(stop-start).count()<<endl;
        cout<<"minVal="<<minVal<<",maxVal="<<maxVal<<endl;

        start = high_resolution_clock::now();
        pair< vector<int>::iterator, vector<int>::iterator > result = 
boost::minmax_element(data.begin(), data.end());
        stop = high_resolution_clock::now();
        cout<<"min_max: 
minmax_element:"<<duration_cast<milliseconds>(stop-start).count()<<endl;	
        cout<<"minVal="<<*result.first<<",maxVal="<<*result.second<<endl;

        minVal = (std::numeric_limits<int>::max)();
        maxVal = (std::numeric_limits<int>::min)();
        start = high_resolution_clock::now();
        for(dataarray::iterator it = data.begin(); it!=data.end();it++)
        {
                minVal = (std::min)(minVal,*it);
                maxVal = (std::max)(maxVal,*it);
        }
        stop = high_resolution_clock::now();
        cout<<"min/max 
handcoded:"<<duration_cast<milliseconds>(stop-start).count()<<endl;	
        cout<<"minVal="<<minVal<<",maxVal="<<maxVal<<endl;

        return 0;
}