convertRootMatricesToJSON.C

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#include "json.hpp"

using std::cout;
using std::string;
using json = nlohmann::json;

std::map<std::string, TGeoHMatrix> *readRootMatrices(std::string filename) {
    cout << "reding file: " << filename << "\n";
    TFile *misalignmentMatrixRootfile = new TFile(filename.c_str(), "READ");
    if (misalignmentMatrixRootfile->IsOpen()) {
        std::map<std::string, TGeoHMatrix> *matrices;
        gDirectory->GetObject("PndLmdMisalignMatrices", matrices);
        misalignmentMatrixRootfile->Close();
        cout << "read " << matrices->size() << " matrices from file.\n";
        return matrices;
    } else {
        cout << "file could not be read\n";
        exit(1);
    }
}

void saveMatricesToJson(std::map<std::string, TGeoHMatrix> matrices, std::string outfilename) {
    // matrices is a map with string->TGeoHMatrix
    json j;
    double thisMatrixDoubles[16];
    TGeoHMatrix thisMatrix;

    for (auto &path : matrices) {
        thisMatrix = path.second;
        thisMatrix.GetHomogenousMatrix(thisMatrixDoubles);

        j[path.first] = {
            thisMatrixDoubles[0], thisMatrixDoubles[1], thisMatrixDoubles[2], thisMatrixDoubles[12],
            thisMatrixDoubles[4], thisMatrixDoubles[5], thisMatrixDoubles[6], thisMatrixDoubles[13],
            thisMatrixDoubles[8], thisMatrixDoubles[9], thisMatrixDoubles[10], thisMatrixDoubles[14],
            thisMatrixDoubles[3], thisMatrixDoubles[7], thisMatrixDoubles[11], thisMatrixDoubles[15]};
    }

    // save!
    cout << "save " << j.size() << " matrices to json!\n";
    std::ofstream o(outfilename.c_str());
    o << std::setw(2) << j << std::endl;
}

void convertRootMatricesToJSON(std::string filename) {
    cout << "starting...\n";

    // read root file, this will be a map<TString, TGeoHMatrix>
    std::map<std::string, TGeoHMatrix> rootMatrices = *(readRootMatrices(filename));

    // save file to json
    cout << "saving " << filename << " to json file!\n";
    saveMatricesToJson(rootMatrices, filename + ".json");
}

// dummy function in case someone calls the macro without argument
void convertRootMatricesToJSON() {
    cout << "You must specify a file name!\n";
    exit(1);
}