Eigen Memory Mapping
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struct point { double a; double b; }; void EigenMapExample() { ////////////////////////////////////////First Example///////////////////////////////////////// Eigen::VectorXd solutionVec(12,1); solutionVec<<1,2,3,4,5,6,7,8,9,10,11,12; Eigen::Map<Eigen::MatrixXd> solutionColMajor(solutionVec.data(),4,3); Eigen::Map<Eigen::Matrix<double, 3, 4, Eigen::RowMajor> >solutionRowMajor (solutionVec.data()); std::cout << "solutionColMajor: "<< std::endl; std::cout << solutionColMajor<< std::endl; std::cout << "solutionRowMajor"<< std::endl; std::cout << solutionRowMajor<< std::endl; ////////////////////////////////////////Second Example///////////////////////////////////////// // https://stackoverflow.com/questions/49813340/stdvectoreigenvector3d-to-eigenmatrixxd-eigen int array[9]; for (int i = 0; i < 9; ++i) { array[i] = i; } Eigen::MatrixXi a(9, 1); a = Eigen::Map<Eigen::Matrix3i>(array); std::cout << a << std::endl; std::vector<point> pointsVec; point point1, point2, point3; point1.a = 1.0; point1.b = 1.5; point2.a = 2.4; point2.b = 3.5; point3.a = -1.3; point3.b = 2.4; pointsVec.push_back(point1); pointsVec.push_back(point2); pointsVec.push_back(point3); Eigen::Matrix2Xd pointsMatrix2d = Eigen::Map<Eigen::Matrix2Xd>( reinterpret_cast<double*>(pointsVec.data()), 2, long(pointsVec.size())); Eigen::MatrixXd pointsMatrixXd = Eigen::Map<Eigen::MatrixXd>( reinterpret_cast<double*>(pointsVec.data()), 2, long(pointsVec.size())); std::cout << pointsMatrix2d << std::endl; std::cout << "==============================" << std::endl; std::cout << pointsMatrixXd << std::endl; std::cout << "==============================" << std::endl; std::vector<Eigen::Vector3d> eigenPointsVec; eigenPointsVec.push_back(Eigen::Vector3d(2, 4, 1)); eigenPointsVec.push_back(Eigen::Vector3d(7, 3, 9)); eigenPointsVec.push_back(Eigen::Vector3d(6, 1, -1)); eigenPointsVec.push_back(Eigen::Vector3d(-6, 9, 8)); Eigen::MatrixXd pointsMatrix = Eigen::Map<Eigen::MatrixXd>(eigenPointsVec[0].data(), 3, long(eigenPointsVec.size())); std::cout << pointsMatrix << std::endl; std::cout << "==============================" << std::endl; pointsMatrix = Eigen::Map<Eigen::MatrixXd>(reinterpret_cast<double*>(eigenPointsVec.data()), 3, long(eigenPointsVec.size())); std::cout << pointsMatrix << std::endl; std::vector<double> aa = { 1, 2, 3, 4 }; Eigen::VectorXd b = Eigen::Map<Eigen::VectorXd, Eigen::Unaligned>(aa.data(), long(aa.size())); } |
