CNetworkOfPoses_impl.h

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          https://www.mrpt.org/                         |
   |                                                                        |
   | Copyright (c) 2005-2020, Individual contributors, see AUTHORS file     |
   | See: https://www.mrpt.org/Authors - All rights reserved.               |
   | Released under BSD License. See: https://www.mrpt.org/License          |
   +------------------------------------------------------------------------+ */
#pragma once

#include <mrpt/graphs/TNodeAnnotations.h>
#include <mrpt/graphs/dijkstra.h>
#include <mrpt/io/CTextFileLinesParser.h>
#include <mrpt/math/CVectorFixed.h>
#include <mrpt/math/TPose2D.h>
#include <mrpt/math/TPose3D.h>
#include <mrpt/math/TPose3DQuat.h>
#include <mrpt/math/matrix_serialization.h>
#include <mrpt/math/ops_matrices.h>  // multiply_*()
#include <mrpt/math/wrap2pi.h>
#include <mrpt/poses/CPose2D.h>
#include <mrpt/poses/CPose3D.h>
#include <mrpt/poses/CPose3DPDFGaussian.h>
#include <mrpt/poses/CPose3DPDFGaussianInf.h>
#include <mrpt/poses/CPose3DQuat.h>
#include <mrpt/poses/CPosePDFGaussian.h>
#include <mrpt/poses/CPosePDFGaussianInf.h>
#include <mrpt/system/string_utils.h>

namespace mrpt::graphs::detail
{
using namespace std;
using namespace mrpt;
using namespace mrpt::poses;
using namespace mrpt::graphs;

template <class POSE_PDF>
struct TPosePDFHelper
{
    static inline void copyFrom2D(POSE_PDF& p, const CPosePDFGaussianInf& pdf)
    {
        p.copyFrom(pdf);
    }
    static inline void copyFrom3D(POSE_PDF& p, const CPose3DPDFGaussianInf& pdf)
    {
        p.copyFrom(pdf);
    }
};
template <>
struct TPosePDFHelper<CPose2D>
{
    static inline void copyFrom2D(CPose2D& p, const CPosePDFGaussianInf& pdf)
    {
        p = pdf.mean;
    }
    static inline void copyFrom3D(CPose2D& p, const CPose3DPDFGaussianInf& pdf)
    {
        p = CPose2D(pdf.mean);
    }
};
template <>
struct TPosePDFHelper<CPose3D>
{
    static inline void copyFrom2D(CPose3D& p, const CPosePDFGaussianInf& pdf)
    {
        p = CPose3D(pdf.mean);
    }
    static inline void copyFrom3D(CPose3D& p, const CPose3DPDFGaussianInf& pdf)
    {
        p = pdf.mean;
    }
};

/// a helper struct with static template functions \sa CNetworkOfPoses
template <class graph_t>
struct graph_ops
{
    static void write_VERTEX_line(
        const TNodeID id, const mrpt::poses::CPose2D& p, std::ostream& f)
    {
        //  VERTEX2 id x y phi
        f << "VERTEX_SE2 " << id << " " << p.x() << " " << p.y() << " "
          << p.phi();
    }
    static void write_VERTEX_line(
        const TNodeID id, const mrpt::poses::CPose3D& p, std::ostream& f)
    {
        //  VERTEX3 id x y z roll pitch yaw
        // **CAUTION** In the TORO graph format angles are in the RPY order vs.
        // MRPT's YPR.
        f << "VERTEX3 " << id << " " << p.x() << " " << p.y() << " " << p.z()
          << " " << p.roll() << " " << p.pitch() << " " << p.yaw();
    }

    static void write_EDGE_line(
        const TPairNodeIDs& edgeIDs, const CPosePDFGaussianInf& edge,
        std::ostream& f)
    {
        //  G2O: EDGE_SE2 from_id to_id Ax Ay Aphi i_xx i_xy i_xp i_yy i_yp
        //  inf_pp
        f << "EDGE_SE2 " << edgeIDs.first << " " << edgeIDs.second << " "
          << edge.mean.x() << " " << edge.mean.y() << " " << edge.mean.phi()
          << " " << edge.cov_inv(0, 0) << " " << edge.cov_inv(0, 1) << " "
          << edge.cov_inv(0, 2) << " " << edge.cov_inv(1, 1) << " "
          << edge.cov_inv(1, 2) << " " << edge.cov_inv(2, 2) << endl;
    }
    static void write_EDGE_line(
        const TPairNodeIDs& edgeIDs, const CPose3DPDFGaussianInf& edge,
        std::ostream& f)
    {
        //  EDGE3 from_id to_id Ax Ay Az Aroll Apitch Ayaw inf_11 inf_12 ..
        //  inf_16 inf_22 .. inf_66
        // **CAUTION** In the TORO graph format angles are in the RPY order vs.
        // MRPT's YPR.
        // **CAUTION** TORO docs say "from_id" "to_id" in the opposite order,
        // but it seems from the data that this is the correct expected format.
        f << "EDGE3 " << edgeIDs.first << " " << edgeIDs.second << " "
          << edge.mean.x() << " " << edge.mean.y() << " " << edge.mean.z()
          << " " << edge.mean.roll() << " " << edge.mean.pitch() << " "
          << edge.mean.yaw() << " " << edge.cov_inv(0, 0) << " "
          << edge.cov_inv(0, 1) << " " << edge.cov_inv(0, 2) << " "
          << edge.cov_inv(0, 5) << " " << edge.cov_inv(0, 4) << " "
          << edge.cov_inv(0, 3) << " " << edge.cov_inv(1, 1) << " "
          << edge.cov_inv(1, 2) << " " << edge.cov_inv(1, 5) << " "
          << edge.cov_inv(1, 4) << " " << edge.cov_inv(1, 3) << " "
          << edge.cov_inv(2, 2) << " " << edge.cov_inv(2, 5) << " "
          << edge.cov_inv(2, 4) << " " << edge.cov_inv(2, 3) << " "
          << edge.cov_inv(5, 5) << " " << edge.cov_inv(5, 4) << " "
          << edge.cov_inv(5, 3) << " " << edge.cov_inv(4, 4) << " "
          << edge.cov_inv(4, 3) << " " << edge.cov_inv(3, 3) << endl;
    }
    static void write_EDGE_line(
        const TPairNodeIDs& edgeIDs, const CPosePDFGaussian& edge,
        std::ostream& f)
    {
        CPosePDFGaussianInf p;
        p.copyFrom(edge);
        write_EDGE_line(edgeIDs, p, f);
    }
    static void write_EDGE_line(
        const TPairNodeIDs& edgeIDs, const CPose3DPDFGaussian& edge,
        std::ostream& f)
    {
        CPose3DPDFGaussianInf p;
        p.copyFrom(edge);
        write_EDGE_line(edgeIDs, p, f);
    }
    static void write_EDGE_line(
        const TPairNodeIDs& edgeIDs, const mrpt::poses::CPose2D& edge,
        std::ostream& f)
    {
        CPosePDFGaussianInf p;
        p.mean = edge;
        p.cov_inv.setIdentity();
        write_EDGE_line(edgeIDs, p, f);
    }
    static void write_EDGE_line(
        const TPairNodeIDs& edgeIDs, const mrpt::poses::CPose3D& edge,
        std::ostream& f)
    {
        CPose3DPDFGaussianInf p;
        p.mean = edge;
        p.cov_inv.setIdentity();
        write_EDGE_line(edgeIDs, p, f);
    }

    static void save_graph_of_poses_to_ostream(
        const graph_t* g, std::ostream& f)
    {
        // 1st: Nodes
        for (const auto& n : g->nodes)
        {
            write_VERTEX_line(n.first, n.second, f);
            // Node annotations:
            const auto sAnnot = n.second.retAnnotsAsString();
            if (!sAnnot.empty()) f << " | " << sAnnot;
            f << endl;
            // Root?
            if (n.first == g->root) f << "FIX " << n.first << endl;
        }

        // 2nd: Edges:
        for (const auto& e : *g)
            if (e.first.first != e.first.second)  // ignore EQUIV edges
                write_EDGE_line(e.first, e.second, f);

    }  // end save_graph

    // =================================================================
    //                     save_graph_of_poses_to_text_file
    // =================================================================
    static void save_graph_of_poses_to_text_file(
        const graph_t* g, const std::string& fil)
    {
        std::ofstream f;
        f.open(fil.c_str());
        if (!f.is_open())
            THROW_EXCEPTION_FMT(
                "Error opening file '%s' for writing", fil.c_str());
        save_graph_of_poses_to_ostream(g, f);
    }

    // =================================================================
    //                     save_graph_of_poses_to_binary_file
    // =================================================================
    static void save_graph_of_poses_to_binary_file(
        const graph_t* g, mrpt::serialization::CArchive& out)
    {
        // Store class name:
        const std::string sClassName =
            mrpt::typemeta::TTypeName<graph_t>::get().c_str();
        out << sClassName;

        // Store serialization version & object data:
        const uint32_t version = 0;
        out << version;
        out << g->nodes << g->edges << g->root;
    }

    // =================================================================
    //                     read_graph_of_poses_from_binary_file
    // =================================================================
    static void read_graph_of_poses_from_binary_file(
        graph_t* g, mrpt::serialization::CArchive& in)
    {
        // Compare class name:
        const std::string sClassName =
            mrpt::typemeta::TTypeName<graph_t>::get().c_str();
        std::string sStoredClassName;
        in >> sStoredClassName;
        ASSERT_EQUAL_(sStoredClassName, sClassName);

        // Check serialization version:
        uint32_t stored_version;
        in >> stored_version;

        g->clear();
        switch (stored_version)
        {
            case 0:
                in >> g->nodes >> g->edges >> g->root;
                break;
            default:
                MRPT_THROW_UNKNOWN_SERIALIZATION_VERSION(stored_version);
        }
    }

    // =================================================================
    //                     load_graph_of_poses_from_text_file
    // =================================================================
    static void load_graph_of_poses_from_text_stream(
        graph_t* g, std::istream& f,
        const std::string& fil = std::string("(none)"))
    {
        using mrpt::system::strCmpI;
        using namespace mrpt::math;

        using CPOSE = typename graph_t::constraint_t;

        set<string> alreadyWarnedUnknowns;  // for unknown line types, show a
        // warning to cerr just once.

        // First, empty the graph:
        g->clear();

        // Determine if it's a 2D or 3D graph, just to raise an error if loading
        // a 3D graph in a 2D one, since
        //  it would be an unintentional loss of information:
        const bool graph_is_3D = CPOSE::is_3D();

        mrpt::io::CTextFileLinesParser filParser(f);

        // -------------------------------------------
        // 1st PASS: Read EQUIV entries only
        //  since processing them AFTER loading the data
        //  is much much slower.
        // -------------------------------------------
        map<TNodeID, TNodeID> lstEquivs;  // List of EQUIV entries: NODEID ->
        // NEWNODEID. NEWNODEID will be always
        // the lowest ID number.

        // Read & process lines each at once until EOF:
        istringstream s;
        while (filParser.getNextLine(s))
        {
            const unsigned int lineNum = filParser.getCurrentLineNumber();
            const string lin = s.str();

            string key;
            if (!(s >> key) || key.empty())
                THROW_EXCEPTION(format(
                    "Line %u: Can't read string for entry type in: '%s'",
                    lineNum, lin.c_str()));

            if (mrpt::system::strCmpI(key, "EQUIV"))
            {
                // Process these ones at the end, for now store in a list:
                TNodeID id1, id2;
                if (!(s >> id1 >> id2))
                    THROW_EXCEPTION(format(
                        "Line %u: Can't read id1 & id2 in EQUIV line: '%s'",
                        lineNum, lin.c_str()));
                lstEquivs[std::max(id1, id2)] = std::min(id1, id2);
            }
        }  // end 1st pass

        // -------------------------------------------
        // 2nd PASS: Read all other entries
        // -------------------------------------------
        filParser.rewind();

        // Read & process lines each at once until EOF:
        while (filParser.getNextLine(s))
        {
            const unsigned int lineNum = filParser.getCurrentLineNumber();
            const string lin = s.str();

            // Recognized strings:
            //  VERTEX2 id x y phi
            //   =(VERTEX_SE2)
            //  EDGE2 from_id to_id Ax Ay Aphi inf_xx inf_xy inf_yy inf_pp
            //  inf_xp inf_yp
            //   =(EDGE or EDGE_SE2 or ODOMETRY)
            //  VERTEX3 id x y z roll pitch yaw
            //  VERTEX_SE3:QUAT id x y z qx qy qz qw
            //  EDGE3 from_id to_id Ax Ay Az Aroll Apitch Ayaw inf_11 inf_12 ..
            //  inf_16 inf_22 .. inf_66
            //  EDGE_SE3:QUAT from_id to_id Ax Ay Az qx qy qz qw inf_11 inf_12
            //  .. inf_16 inf_22 .. inf_66
            //  EQUIV id1 id2
            string key;
            if (!(s >> key) || key.empty())
                THROW_EXCEPTION(format(
                    "Line %u: Can't read string for entry type in: '%s'",
                    lineNum, lin.c_str()));

            if (strCmpI(key, "VERTEX2") || strCmpI(key, "VERTEX") ||
                strCmpI(key, "VERTEX_SE2"))
            {
                TNodeID id;
                TPose2D p2D;
                if (!(s >> id >> p2D.x >> p2D.y >> p2D.phi))
                    THROW_EXCEPTION(format(
                        "Line %u: Error parsing VERTEX2 line: '%s'", lineNum,
                        lin.c_str()));

                // Make sure the node is new:
                if (g->nodes.find(id) != g->nodes.end())
                    THROW_EXCEPTION(format(
                        "Line %u: Error, duplicated verted ID %u in line: "
                        "'%s'",
                        lineNum, static_cast<unsigned int>(id), lin.c_str()));

                // EQUIV? Replace ID by new one.
                {
                    const auto itEq = lstEquivs.find(id);
                    if (itEq != lstEquivs.end()) id = itEq->second;
                }

                // Add to map: ID -> absolute pose:
                if (g->nodes.find(id) == g->nodes.end())
                {
                    using pose_t = typename CNetworkOfPoses<
                        CPOSE>::constraint_t::type_value;
                    pose_t& newNode = g->nodes[id];
                    newNode = pose_t(CPose2D(
                        p2D));  // Convert to mrpt::poses::CPose3D if needed
                }
            }
            else if (strCmpI(key, "VERTEX3"))
            {
                if (!graph_is_3D)
                    THROW_EXCEPTION(format(
                        "Line %u: Try to load VERTEX3 into a 2D graph: "
                        "'%s'",
                        lineNum, lin.c_str()));

                //  VERTEX3 id x y z roll pitch yaw
                TNodeID id;
                TPose3D p3D;
                // **CAUTION** In the TORO graph format angles are in the RPY
                // order vs. MRPT's YPR.
                if (!(s >> id >> p3D.x >> p3D.y >> p3D.z >> p3D.roll >>
                      p3D.pitch >> p3D.yaw))
                    THROW_EXCEPTION(format(
                        "Line %u: Error parsing VERTEX3 line: '%s'", lineNum,
                        lin.c_str()));

                // Make sure the node is new:
                if (g->nodes.find(id) != g->nodes.end())
                    THROW_EXCEPTION(format(
                        "Line %u: Error, duplicated verted ID %u in line: "
                        "'%s'",
                        lineNum, static_cast<unsigned int>(id), lin.c_str()));

                // EQUIV? Replace ID by new one.
                {
                    const auto itEq = lstEquivs.find(id);
                    if (itEq != lstEquivs.end()) id = itEq->second;
                }

                // Add to map: ID -> absolute pose:
                if (g->nodes.find(id) == g->nodes.end())
                {
                    g->nodes[id] = typename CNetworkOfPoses<CPOSE>::
						constraint_t::type_value(CPose3D(
                            p3D));  // Auto converted to CPose2D if needed
                }
            }
            else if (strCmpI(key, "VERTEX_SE3:QUAT"))
            {
                if (!graph_is_3D)
                    THROW_EXCEPTION(format(
                        "Line %u: Try to load VERTEX_SE3:QUAT into a 2D "
                        "graph: '%s'",
                        lineNum, lin.c_str()));

                // VERTEX_SE3:QUAT id x y z qx qy qz qw
                TNodeID id;
                TPose3DQuat p3D;
                if (!(s >> id >> p3D.x >> p3D.y >> p3D.z >> p3D.qx >> p3D.qy >>
                      p3D.qz >> p3D.qr))
                    THROW_EXCEPTION(format(
                        "Line %u: Error parsing VERTEX_SE3:QUAT line: '%s'",
                        lineNum, lin.c_str()));

                // Make sure the node is new:
                if (g->nodes.find(id) != g->nodes.end())
                    THROW_EXCEPTION(format(
                        "Line %u: Error, duplicated verted ID %u in line: "
                        "'%s'",
                        lineNum, static_cast<unsigned int>(id), lin.c_str()));

                // EQUIV? Replace ID by new one.
                {
                    const auto itEq = lstEquivs.find(id);
                    if (itEq != lstEquivs.end()) id = itEq->second;
                }

                // Add to map: ID -> absolute pose:
                if (g->nodes.find(id) == g->nodes.end())
                {
                    g->nodes[id] = typename CNetworkOfPoses<CPOSE>::
						constraint_t::type_value(
                            CPose3D(CPose3DQuat(p3D)));  // Auto converted to
                    // CPose2D if needed
                }
            }
            else if (
                strCmpI(key, "EDGE2") || strCmpI(key, "EDGE") ||
                strCmpI(key, "ODOMETRY") || strCmpI(key, "EDGE_SE2"))
            {
                //  EDGE_SE2 from_id to_id Ax Ay Aphi inf_xx i_xy i_xp i_yy i_yp
                //  i_pp Read values are:
                //    [ s00 s01 s02 ]
                //    [  -  s11 s12 ]
                //    [  -   -  s22 ]
                //
                TNodeID to_id, from_id;
                if (!(s >> from_id >> to_id))
                    THROW_EXCEPTION(format(
                        "Line %u: Error parsing EDGE2 line: '%s'", lineNum,
                        lin.c_str()));

                // EQUIV? Replace ID by new one.
                {
                    const auto itEq = lstEquivs.find(to_id);
                    if (itEq != lstEquivs.end()) to_id = itEq->second;
                }
                {
                    const auto itEq = lstEquivs.find(from_id);
                    if (itEq != lstEquivs.end()) from_id = itEq->second;
                }

                if (from_id != to_id)  // Don't load self-edges! (probably come
                // from an EQUIV)
                {
                    TPose2D Ap_mean;
                    mrpt::math::CMatrixDouble33 Ap_cov_inv;
                    if (!(s >> Ap_mean.x >> Ap_mean.y >> Ap_mean.phi >>
                          Ap_cov_inv(0, 0) >> Ap_cov_inv(0, 1) >>
                          Ap_cov_inv(0, 2) >> Ap_cov_inv(1, 1) >>
                          Ap_cov_inv(1, 2) >> Ap_cov_inv(2, 2)))
                        THROW_EXCEPTION(format(
                            "Line %u: Error parsing EDGE2 line: '%s'", lineNum,
                            lin.c_str()));

                    // Complete low triangular part of inf matrix:
                    Ap_cov_inv(1, 0) = Ap_cov_inv(0, 1);
                    Ap_cov_inv(2, 0) = Ap_cov_inv(0, 2);
                    Ap_cov_inv(2, 1) = Ap_cov_inv(1, 2);

                    // Convert to 2D cov, 3D cov or 3D inv_cov as needed:
                    typename CNetworkOfPoses<CPOSE>::edge_t newEdge;
                    TPosePDFHelper<CPOSE>::copyFrom2D(
                        newEdge,
                        CPosePDFGaussianInf(CPose2D(Ap_mean), Ap_cov_inv));
                    g->insertEdge(from_id, to_id, newEdge);
                }
            }
            else if (strCmpI(key, "EDGE3"))
            {
                if (!graph_is_3D)
                    THROW_EXCEPTION(format(
                        "Line %u: Try to load EDGE3 into a 2D graph: '%s'",
                        lineNum, lin.c_str()));

                //  EDGE3 from_id to_id Ax Ay Az Aroll Apitch Ayaw inf_11 inf_12
                //  .. inf_16 inf_22 .. inf_66
                TNodeID to_id, from_id;
                if (!(s >> from_id >> to_id))
                    THROW_EXCEPTION(format(
                        "Line %u: Error parsing EDGE3 line: '%s'", lineNum,
                        lin.c_str()));

                // EQUIV? Replace ID by new one.
                {
                    const auto itEq = lstEquivs.find(to_id);
                    if (itEq != lstEquivs.end()) to_id = itEq->second;
                }
                {
                    const auto itEq = lstEquivs.find(from_id);
                    if (itEq != lstEquivs.end()) from_id = itEq->second;
                }

                if (from_id != to_id)  // Don't load self-edges! (probably come
                // from an EQUIV)
                {
                    TPose3D Ap_mean;
                    mrpt::math::CMatrixDouble66 Ap_cov_inv;
                    // **CAUTION** In the TORO graph format angles are in the
                    // RPY order vs. MRPT's YPR.
                    if (!(s >> Ap_mean.x >> Ap_mean.y >> Ap_mean.z >>
                          Ap_mean.roll >> Ap_mean.pitch >> Ap_mean.yaw))
                        THROW_EXCEPTION(format(
                            "Line %u: Error parsing EDGE3 line: '%s'", lineNum,
                            lin.c_str()));

                    // **CAUTION** Indices are shuffled to the change YAW(3) <->
                    // ROLL(5) in the order of the data.
                    if (!(s >> Ap_cov_inv(0, 0) >> Ap_cov_inv(0, 1) >>
                          Ap_cov_inv(0, 2) >> Ap_cov_inv(0, 5) >>
                          Ap_cov_inv(0, 4) >> Ap_cov_inv(0, 3) >>
                          Ap_cov_inv(1, 1) >> Ap_cov_inv(1, 2) >>
                          Ap_cov_inv(1, 5) >> Ap_cov_inv(1, 4) >>
                          Ap_cov_inv(1, 3) >> Ap_cov_inv(2, 2) >>
                          Ap_cov_inv(2, 5) >> Ap_cov_inv(2, 4) >>
                          Ap_cov_inv(2, 3) >> Ap_cov_inv(5, 5) >>
                          Ap_cov_inv(5, 4) >> Ap_cov_inv(5, 3) >>
                          Ap_cov_inv(4, 4) >> Ap_cov_inv(4, 3) >>
                          Ap_cov_inv(3, 3)))
                    {
                        // Cov may be omitted in the file:
                        Ap_cov_inv.setIdentity();

                        if (alreadyWarnedUnknowns.find("MISSING_3D") ==
                            alreadyWarnedUnknowns.end())
                        {
                            alreadyWarnedUnknowns.insert("MISSING_3D");
                            cerr << "[CNetworkOfPoses::loadFromTextFile] "
                                 << fil << ":" << lineNum
                                 << ": Warning: Information matrix missing, "
                                    "assuming unity.\n";
                        }
                    }
                    else
                    {
                        // Complete low triangular part of inf matrix:
                        for (size_t r = 1; r < 6; r++)
                            for (size_t c = 0; c < r; c++)
                                Ap_cov_inv(r, c) = Ap_cov_inv(c, r);
                    }

                    // Convert as needed:
                    typename CNetworkOfPoses<CPOSE>::edge_t newEdge;
                    TPosePDFHelper<CPOSE>::copyFrom3D(
                        newEdge,
                        CPose3DPDFGaussianInf(CPose3D(Ap_mean), Ap_cov_inv));
                    g->insertEdge(from_id, to_id, newEdge);
                }
            }
            else if (strCmpI(key, "EDGE_SE3:QUAT"))
            {
                if (!graph_is_3D)
                    THROW_EXCEPTION(format(
                        "Line %u: Try to load EDGE3 into a 2D graph: '%s'",
                        lineNum, lin.c_str()));

                //  EDGE_SE3:QUAT from_id to_id Ax Ay Az qx qy qz qw inf_11
                //  inf_12 .. inf_16 inf_22 .. inf_66
                //  EDGE3 from_id to_id Ax Ay Az Aroll Apitch Ayaw inf_11 inf_12
                //  .. inf_16 inf_22 .. inf_66
                TNodeID to_id, from_id;
                if (!(s >> from_id >> to_id))
                    THROW_EXCEPTION(format(
                        "Line %u: Error parsing EDGE_SE3:QUAT line: '%s'",
                        lineNum, lin.c_str()));

                // EQUIV? Replace ID by new one.
                {
                    const auto itEq = lstEquivs.find(to_id);
                    if (itEq != lstEquivs.end()) to_id = itEq->second;
                }
                {
                    const auto itEq = lstEquivs.find(from_id);
                    if (itEq != lstEquivs.end()) from_id = itEq->second;
                }

                if (from_id != to_id)  // Don't load self-edges! (probably come
                // from an EQUIV)
                {
                    TPose3DQuat Ap_mean;
                    mrpt::math::CMatrixDouble66 Ap_cov_inv;
                    if (!(s >> Ap_mean.x >> Ap_mean.y >> Ap_mean.z >>
                          Ap_mean.qx >> Ap_mean.qy >> Ap_mean.qz >> Ap_mean.qr))
                        THROW_EXCEPTION(format(
                            "Line %u: Error parsing EDGE_SE3:QUAT line: "
                            "'%s'",
                            lineNum, lin.c_str()));

                    // **CAUTION** Indices are shuffled to the change YAW(3) <->
                    // ROLL(5) in the order of the data.
                    if (!(s >> Ap_cov_inv(0, 0) >> Ap_cov_inv(0, 1) >>
                          Ap_cov_inv(0, 2) >> Ap_cov_inv(0, 5) >>
                          Ap_cov_inv(0, 4) >> Ap_cov_inv(0, 3) >>
                          Ap_cov_inv(1, 1) >> Ap_cov_inv(1, 2) >>
                          Ap_cov_inv(1, 5) >> Ap_cov_inv(1, 4) >>
                          Ap_cov_inv(1, 3) >> Ap_cov_inv(2, 2) >>
                          Ap_cov_inv(2, 5) >> Ap_cov_inv(2, 4) >>
                          Ap_cov_inv(2, 3) >> Ap_cov_inv(5, 5) >>
                          Ap_cov_inv(5, 4) >> Ap_cov_inv(5, 3) >>
                          Ap_cov_inv(4, 4) >> Ap_cov_inv(4, 3) >>
                          Ap_cov_inv(3, 3)))
                    {
                        // Cov may be omitted in the file:
                        Ap_cov_inv.setIdentity();

                        if (alreadyWarnedUnknowns.find("MISSING_3D") ==
                            alreadyWarnedUnknowns.end())
                        {
                            alreadyWarnedUnknowns.insert("MISSING_3D");
                            cerr << "[CNetworkOfPoses::loadFromTextFile] "
                                 << fil << ":" << lineNum
                                 << ": Warning: Information matrix missing, "
                                    "assuming unity.\n";
                        }
                    }
                    else
                    {
                        // Complete low triangular part of inf matrix:
                        for (size_t r = 1; r < 6; r++)
                            for (size_t c = 0; c < r; c++)
                                Ap_cov_inv(r, c) = Ap_cov_inv(c, r);
                    }

                    // Convert as needed:
                    typename CNetworkOfPoses<CPOSE>::edge_t newEdge;
                    TPosePDFHelper<CPOSE>::copyFrom3D(
                        newEdge,
                        CPose3DPDFGaussianInf(
                            CPose3D(CPose3DQuat(Ap_mean)), Ap_cov_inv));
                    g->insertEdge(from_id, to_id, newEdge);
                }
            }
            else if (strCmpI(key, "EQUIV"))
            {
                // Already read in the 1st pass.
            }
            else if (strCmpI(key, "FIX"))
            {
                TNodeID id;
                if (!(s >> id))
                    THROW_EXCEPTION(format(
                        "Line %u: Can't read id in FIX line: '%s'", lineNum,
                        lin.c_str()));
                g->root = id;
            }
            else
            {  // Unknown entry: Warn the user just once:
                if (alreadyWarnedUnknowns.find(key) ==
                    alreadyWarnedUnknowns.end())
                {
                    alreadyWarnedUnknowns.insert(key);
                    cerr << "[CNetworkOfPoses::loadFromTextFile] " << fil << ":"
                         << lineNum << ": Warning: unknown entry type: " << key
                         << endl;
                }
            }
        }  // end while

    }  // end load_graph

    static void load_graph_of_poses_from_text_file(
        graph_t* g, const std::string& fil)
    {
        std::ifstream f(fil);
        if (!f.is_open())
            THROW_EXCEPTION_FMT(
                "Error opening file '%s' for reading", fil.c_str());
        load_graph_of_poses_from_text_stream(g, f, fil);
    }

    // --------------------------------------------------------------------------------
    //               Implements: collapseDuplicatedEdges
    //
    // Look for duplicated edges (even in opposite directions) between all pairs
    // of nodes and fuse them.
    //  Upon return, only one edge remains between each pair of nodes with the
    //  mean
    //   & covariance (or information matrix) corresponding to the Bayesian
    //   fusion of all the Gaussians.
    // --------------------------------------------------------------------------------
    static size_t graph_of_poses_collapse_dup_edges(graph_t* g)
    {
        MRPT_START
        using TEdgeIterator = typename graph_t::edges_map_t::iterator;

        // Data structure: (id1,id2) -> all edges between them
        //  (with id1 < id2)
        using TListAllEdges =
            map<pair<TNodeID, TNodeID>,
                vector<TEdgeIterator>>;  // For god's sake... when will ALL
        // compilers support
        // auto!! :'-(
        TListAllEdges lstAllEdges;

        // Clasify all edges to identify duplicated ones:
        for (auto itEd = g->edges.begin(); itEd != g->edges.end(); ++itEd)
        {
            // Build a pair <id1,id2> with id1 < id2:
            const pair<TNodeID, TNodeID> arc_id = make_pair(
                std::min(itEd->first.first, itEd->first.second),
                std::max(itEd->first.first, itEd->first.second));
            // get (or create the first time) the list of edges between them:
            vector<TEdgeIterator>& lstEdges = lstAllEdges[arc_id];
            // And add this one:
            lstEdges.push_back(itEd);
        }

        // Now, remove all but the first edge:
        size_t nRemoved = 0;
        for (auto it = lstAllEdges.begin(); it != lstAllEdges.end(); ++it)
        {
            const size_t N = it->second.size();
            for (size_t i = 1; i < N; i++)  // i=0 is NOT removed
                g->edges.erase(it->second[i]);

            if (N >= 2) nRemoved += N - 1;
        }

        return nRemoved;
        MRPT_END
    }  // end of graph_of_poses_collapse_dup_edges

    // --------------------------------------------------------------------------------
    //               Implements: dijkstra_nodes_estimate
    //
    //  Compute a simple estimation of the global coordinates of each node just
    // from the information in all edges, sorted in a Dijkstra tree based on the
    // current "root" node.
    //  Note that "global" coordinates are with respect to the node with the ID
    // specified in \a root.
    // --------------------------------------------------------------------------------
    static void graph_of_poses_dijkstra_init(
        graph_t* g, std::map<TNodeID, size_t>* topological_distances = nullptr)
    {
        MRPT_START
        using namespace std;

        // Do Dijkstra shortest path from "root" to all other nodes:
        using dijkstra_t =
            CDijkstra<graph_t, typename graph_t::maps_implementation_t>;
        using constraint_t = typename graph_t::constraint_t;

        // initialize corresponding dijkstra object from root.
        dijkstra_t dijkstra(*g, g->root);

        // Get the tree representation of the graph and traverse it
        //  from its root toward the leafs:
        typename dijkstra_t::tree_graph_t treeView;
        dijkstra.getTreeGraph(treeView);

        // This visitor class performs the real job of
        struct VisitorComputePoses : public dijkstra_t::tree_graph_t::Visitor
        {
            graph_t* m_g;  // The original graph
            std::map<TNodeID, size_t>* m_topo_dists{nullptr};

            VisitorComputePoses(graph_t* g) : m_g(g) {}
            void OnVisitNode(
                const TNodeID parent_id,
                const typename dijkstra_t::tree_graph_t::Visitor::tree_t::
                    TEdgeInfo& edge_to_child,
                [[maybe_unused]] const size_t depth_level) override
            {
                const TNodeID child_id = edge_to_child.id;

                // topological distance:
                if (m_topo_dists) (*m_topo_dists)[child_id] = depth_level;

                // Compute the pose of "child_id" as parent_pose (+)
                // edge_delta_pose,
                //  taking into account that that edge may be in reverse order
                //  and then have to invert the delta_pose:
                if ((!edge_to_child.reverse &&
                     !m_g->edges_store_inverse_poses) ||
                    (edge_to_child.reverse && m_g->edges_store_inverse_poses))
                {  // pose_child = p_parent (+) p_delta
                    m_g->nodes[child_id].composeFrom(
                        m_g->nodes[parent_id],
                        edge_to_child.data->getPoseMean());
                }
                else
                {  // pose_child = p_parent (+) [(-)p_delta]
                    m_g->nodes[child_id].composeFrom(
                        m_g->nodes[parent_id],
                        -edge_to_child.data->getPoseMean());
                }
            }
        };

        // Remove all global poses except for the root node, which is the
        // origin:
        //
        // Keep track of the NODE_ANNOTATIONS for each node and put it after
        // the global pose computation
        bool empty_node_annots = g->nodes.begin()->second.is_node_annots_empty;
        map<const TNodeID, TNodeAnnotations*> nodeID_to_annots;
        if (!empty_node_annots)
        {
            for (auto poses_cit = g->nodes.begin(); poses_cit != g->nodes.end();
                 ++poses_cit)
            {
                nodeID_to_annots.insert(make_pair(
                    poses_cit->first, poses_cit->second.getCopyOfAnnots()));
            }
        }

        g->nodes.clear();
        g->nodes[g->root] =
            typename constraint_t::type_value();  // Typ: CPose2D() or CPose3D()

        // Run the visit thru all nodes in the tree:
        VisitorComputePoses myVisitor(g);
        myVisitor.m_topo_dists = topological_distances;
        treeView.visitBreadthFirst(treeView.root, myVisitor);

        // The distance of "root" is zero (it's not visited in the loop above!):
        if (topological_distances) (*topological_distances)[g->root] = 0;

        // Fill the NODE_ANNOTATIONS part again
        if (!empty_node_annots)
        {
            for (auto poses_cit = g->nodes.begin(); poses_cit != g->nodes.end();
                 ++poses_cit)
            {
                TNodeAnnotations* node_annots =
                    nodeID_to_annots.at(poses_cit->first);
                bool res = poses_cit->second.setAnnots(*node_annots);

                // free dynamically allocated mem
                delete node_annots;
                node_annots = nullptr;

                // make sure setting annotations was successful
                ASSERTMSG_(
                    res, mrpt::format(
                             "Setting annotations for nodeID \"%lu\" was "
                             "unsuccessful",
                             static_cast<unsigned long>(poses_cit->first)));
            }
        }

        MRPT_END
    }  // end of graph_of_poses_dijkstra_init

    // Auxiliary funcs:
    template <class VEC>
    static inline double auxMaha2Dist(VEC& err, const CPosePDFGaussianInf& p)
    {
        math::wrapToPiInPlace(err[2]);
        return mrpt::math::multiply_HtCH_scalar(err, p.cov_inv);
    }
    template <class VEC>
    static inline double auxMaha2Dist(VEC& err, const CPose3DPDFGaussianInf& p)
    {
        math::wrapToPiInPlace(err[3]);
        math::wrapToPiInPlace(err[4]);
        math::wrapToPiInPlace(err[5]);
        return mrpt::math::multiply_HtCH_scalar(err, p.cov_inv);
    }
    template <class VEC>
    static inline double auxMaha2Dist(VEC& err, const CPosePDFGaussian& p)
    {
        math::wrapToPiInPlace(err[2]);
        // err^t*cov_inv*err
        return mrpt::math::multiply_HCHt_scalar(err, p.cov.inverse_LLt());
    }
    template <class VEC>
    static inline double auxMaha2Dist(VEC& err, const CPose3DPDFGaussian& p)
    {
        math::wrapToPiInPlace(err[3]);
        math::wrapToPiInPlace(err[4]);
        math::wrapToPiInPlace(err[5]);
        // err^t*cov_inv*err
        return mrpt::math::multiply_HtCH_scalar(err, p.cov.inverse_LLt());
    }
    // These two are for simulating maha2 distances for non-PDF types: fallback
    // to squared-norm:
    template <class VEC>
    static inline double auxMaha2Dist(VEC& err, const mrpt::poses::CPose2D& p)
    {
        math::wrapToPiInPlace(err[2]);
        return square(err[0]) + square(err[1]) + square(err[2]);
    }
    template <class VEC>
    static inline double auxMaha2Dist(VEC& err, const mrpt::poses::CPose3D& p)
    {
        math::wrapToPiInPlace(err[3]);
        math::wrapToPiInPlace(err[4]);
        math::wrapToPiInPlace(err[5]);
        return square(err[0]) + square(err[1]) + square(err[2]) +
               square(err[3]) + square(err[4]) + square(err[5]);
    }

    static inline double auxEuclid2Dist(
        const mrpt::poses::CPose2D& p1, const mrpt::poses::CPose2D& p2)
    {
        return square(p1.x() - p2.x()) + square(p1.y() - p2.y()) +
               square(mrpt::math::wrapToPi(p1.phi() - p2.phi()));
    }
    static inline double auxEuclid2Dist(
        const mrpt::poses::CPose3D& p1, const mrpt::poses::CPose3D& p2)
    {
        return square(p1.x() - p2.x()) + square(p1.y() - p2.y()) +
               square(p1.z() - p2.z()) +
               square(mrpt::math::wrapToPi(p1.yaw() - p2.yaw())) +
               square(mrpt::math::wrapToPi(p1.pitch() - p2.pitch())) +
               square(mrpt::math::wrapToPi(p1.roll() - p2.roll()));
    }

    // --------------------------------------------------------------------------------
    //               Implements: detail::graph_edge_sqerror
    //
    //  Compute the square error of a single edge, in comparison to the nodes
    // global poses.
    // --------------------------------------------------------------------------------
    static double graph_edge_sqerror(
        const graph_t* g,
        const typename mrpt::graphs::CDirectedGraph<
            typename graph_t::constraint_t>::edges_map_t::const_iterator&
            itEdge,
        bool ignoreCovariances)
    {
        MRPT_START

        // Get node IDs:
        const TNodeID from_id = itEdge->first.first;
        const TNodeID to_id = itEdge->first.second;

        // And their global poses as stored in "nodes"
        auto itPoseFrom = g->nodes.find(from_id);
        auto itPoseTo = g->nodes.find(to_id);
        ASSERTMSG_(
            itPoseFrom != g->nodes.end(),
            format(
                "Node %u doesn't have a global pose in 'nodes'.",
                static_cast<unsigned int>(from_id)));
        ASSERTMSG_(
            itPoseTo != g->nodes.end(),
            format(
                "Node %u doesn't have a global pose in 'nodes'.",
                static_cast<unsigned int>(to_id)));

        // The global poses:
        using constraint_t = typename graph_t::constraint_t;

        const typename constraint_t::type_value& from_mean = itPoseFrom->second;
        const typename constraint_t::type_value& to_mean = itPoseTo->second;

        // The delta_pose as stored in the edge:
        const constraint_t& edge_delta_pose = itEdge->second;
        const typename constraint_t::type_value& edge_delta_pose_mean =
            edge_delta_pose.getPoseMean();

        if (ignoreCovariances)
        {  // Square Euclidean distance: Just use the mean values, ignore covs.
            // from_plus_delta = from_mean (+) edge_delta_pose_mean
            typename constraint_t::type_value from_plus_delta(
                UNINITIALIZED_POSE);
            from_plus_delta.composeFrom(from_mean, edge_delta_pose_mean);

            // (auxMaha2Dist will also take into account the 2PI wrapping)
            return auxEuclid2Dist(from_plus_delta, to_mean);
        }
        else
        {
            // Square Mahalanobis distance
            // from_plus_delta = from_mean (+) edge_delta_pose (as a Gaussian)
            constraint_t from_plus_delta = edge_delta_pose;
            from_plus_delta.changeCoordinatesReference(from_mean);

            // "from_plus_delta" is now a 3D or 6D Gaussian, to be compared to
            // "to_mean":
            //  We want to compute the squared Mahalanobis distance:
            //       err^t * INV_COV * err
            //
            mrpt::math::CVectorFixedDouble<
                constraint_t::type_value::static_size>
                err;
            for (size_t i = 0; i < constraint_t::type_value::static_size; i++)
                err[i] = from_plus_delta.getPoseMean()[i] - to_mean[i];

            // (auxMaha2Dist will also take into account the 2PI wrapping)
            return auxMaha2Dist(err, from_plus_delta);
        }
        MRPT_END
    }

};  // end of graph_ops<graph_t>

}  // namespace mrpt::graphs::detail