Class for management global instances of data sinks (e.g. histograms, trees).

See process diagram for further information.

minimal example

class MyProcessor : public Processor {
    // ...
private:
    H1FEntry _hist; // 1D histogram with float weights
};

void MyProcessor::init() {
    _hist = ProcessorApi::Book::bookH1F(
        this,
        "/path/in/result/file/",
        "name",
        "the histogram title",
        {"axis title", nBins, min, max} // AxisConfiguration
    );  
}

void MyProcessor::processEvent(EventStore* event)
    H1FHandle histHandle = _hist.handle();
    for(/*...*/) {
        histHandle.fill(
            {x}, // point type: e.g.  '{x,y}' for 2D, etc.
            weight);
    }
}

store histograms in array

class MyProcessor : public Processor {
    // ...
private:
    std::array<Hist1F, 3> _hist1fs; // 1D histograms with float weights
};

void MyProcessor::init() {
    int i = 0;
    for(auto& hist : _hist1fs) {
        hist = ProcessorApi::Book::bookH1F(
            this,
            "/path/in/reslult/file/" + std::to_string(i++) + "/",
            "name",
            "the histogram title",
            {"axis title", nBins, min, max} // AxisConfiguration
        );  
    }
}

void MyProcessor::processEvent(EventStore* event)

    std::array<H1FHandle, _hist1fs.size()> histHandles;
    std::transform(_hist1fs.begin(), _hist1fs.end(),
        histHandle.begin(), [](auto& hist){return hist.hanlde();});

    for(/*...*/) {
        histHandles[i].fill(
            {x}, // point type: e.g.  '{x,y}' for 2D, etc.
            weight);
    }
}

store histograms in vector

class MyProcessor : public Processor {
    // ...
private:
    std::vector<Hist2F> _hist2fs; // 2D histograms with float weights
};

void MyProcessor::init() {
    for(int i = 0; i < 10; ++i) {
        _hist2fs.emplace_back(
            ProcessorApi::Book::bookH2F(
                this,
                "/path/" + std::to_string(i) + "/",
                "name",
                "title",
                {"x", nBins, min, max},
                {"y", nBins, min, max}
            )
        );
    }
}

void MyProcessor::processEvent(EventStore* event)

    std::vector<H2FHandle> histHandles;
    std::transform(_hist2fs.begin(), _hist2fs.end(),
        std::bak_inserter(histHandle), [](auto& hist){return hist.hanlde();});

    for(/*...*/) {
        histHandles[i].fill(
            {x,y},
            weight);
    }
}

book functions

See reference manual for more details.
For listing of Histogram types see MarlinBookConfig.h

// dim… dimenision of data points(1, 2, and 3 are supported)
// w_t… type of weight, F… float, D… double, I… interger
Hist/*dim*//*w_t*/ hist = book/*dim*//*w_t*/(
    Processor* proc, 
    const std::filesystem::path& path,
    const std::string& name,
    const std::string& title,
    const Hist/*dim*//*w_t*/::AxisConfig_t& axis1,
    [const Hist/*dim*//*w_t*/::AxisConfig_t& axis2,]
    [const Hist/*dim*//*w_t*/::AxisConfig_t& axis3,]
    [BookFlag_t = BookFlags::Default]
);

search if histogram already exist, if not create new histogram, then return Entry to histogram.

fill functions

// add single point
handle.fill(Point_t, Weight_t)   

// fill multiple entries at one with fillN, use for this an array or vector data structure    
handle.fillN(std::array<Point_t>, std::array<Weight_t>)   
handle.fillN(std::vector<Point_t>, std::vector<Weight_t>)   

handle function

ONLY use in processEvent, and only as locale variable!!