histogram.cpp

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// Xerus - A General Purpose Tensor Library
// Copyright (C) 2014-2017 Benjamin Huber and Sebastian Wolf. 
// 
// Xerus is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License,
// or (at your option) any later version.
// 
// Xerus is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
// 
// You should have received a copy of the GNU Affero General Public License
// along with Xerus. If not, see <http://www.gnu.org/licenses/>.
//
// For further information on Xerus visit https://libXerus.org 
// or contact us at contact@libXerus.org.

#include <xerus/misc/histogram.h>
#include <xerus/misc.h>
#include <xerus/misc/internal.h>

namespace xerus { namespace misc {

    LogHistogram::LogHistogram(const double _base) : base(_base), totalCount(0) {}
    
    LogHistogram &LogHistogram::operator+=(const LogHistogram &_other) {
        REQUIRE(misc::approx_equal(_other.base, base), "only histograms of identical base can be added");
        for (const auto &h : _other.buckets) {
            buckets[h.first] += h.second;
        }
        totalCount += _other.totalCount;
        return *this;
    }
    
    void LogHistogram::add(double _value, size_t _count) {
        double logRate = log(_value)/log(base);
        REQUIRE(std::isfinite(_value), "tried to add illegal value " << _value << " into a histogram");
        buckets[int(logRate)] += _count;
        totalCount += _count;
    }
    
    LogHistogram LogHistogram::read_from_file(const std::string &_fileName) {
        std::ifstream in(_fileName);
        LogHistogram result(0.0);
        std::string line;
        std::getline(in, line);
        REQUIRE(line == "# raw data:", "unknown histogram file format " << _fileName); //TODO this should throw an exception
        char c;
        in >> c;
        REQUIRE(c == '#', "missing information in histogram file " << _fileName);
        in >> result.base >> result.totalCount;
        std::getline(in, line); // read in rest of this line
        std::getline(in, line); // line now contains all buckets
        std::stringstream bucketData(line);
        bucketData >> c;
        REQUIRE(c == '#', "missing information in histogram file " << _fileName);
        int bucketIndex;
        while (bucketData >> bucketIndex) {
            size_t count;
            if (!(bucketData >> count)) {
                LOG(fatal, "missing bucket count in histogram file " << _fileName);
            }
            result.buckets[bucketIndex] = count;
        }
        size_t accountedTime=0;
        for (auto &h : result.buckets) {
            accountedTime += h.second;
        }
        REQUIRE(accountedTime == result.totalCount, "histogram data inconsistent in file " << _fileName);
        return result;
    }
    
    void LogHistogram::dump_to_file(const std::string &_fileName) const {
        std::ofstream out(_fileName);
        out << "# raw data:\n";
        out << "# " << base << ' ' << totalCount << '\n';
        out << '#';
        for (auto &h : buckets) {
            out << ' ' << h.first << ' ' << h.second;
        }
        out << "\n# plotable data:\n";
        if (!buckets.empty()) {
            int firstOutput = buckets.begin()->first - 1;
            int lastOutput = buckets.rbegin()->first + 1;
            for (int i=firstOutput; i<=lastOutput; ++i) {
                out << pow(base, i) << ' ';
                if (buckets.count(i) > 0) {
                    out << double(buckets.find(i)->second)/double(totalCount) << '\n';
                } else {
                    out << "0\n";
                }
            }
        }
        out.close();
    }

} // namespace misc
} // namespace xerus