Eigen::Matrix与array数据转换
1. 数组转化为Eigen::Matrix
int array[9]; cout << "colMajor matrix = \n" << Map<Matrix3i>(array) << endl; // map a contiguous array as a column-major matrix cout << "rowMajor matrix = \n" << Map<Matrix<int, 3, 3, RowMajor>>(array) << endl; // map a contiguous array as a row-major matrix Map<MatrixXi> eigMat1(array, 3, 3); // eigMat1和array指向的是同一个内存空间，是绑定在一起的 MatrixXi eigMat2 = Map<MatrixXi>(array, 3, 3); // eigMat1和array指向不同的内存空间，互不影响
2. Eigen::Matrix转化为数组
Matrix3d eigMat; double* eigMatptr = eigMat.data(); double* eigMatptrnew = new double[eigMat.size()]; Map<MatrixXd>(eigMatptrnew, eigMat.rows(), eigMat.cols()) = eigMat;
3.更多转化
下面的代码是我写的互相转化的测试
#include <iostream> #include <vector> #include <Eigen/Dense> using namespace std; using namespace Eigen; void array2eigenMat(); void eigenMat2array(); void array2eigenVec(); void eigenVec2array(); void vector2eigenMat(); void eigenMat2vector(); void vector2eigenVec(); void eigenVec2vector(); int main() { cout << "hello world" <<endl; array2eigenMat(); eigenMat2array(); array2eigenVec(); eigenVec2array(); vector2eigenMat(); eigenMat2vector(); vector2eigenVec(); eigenVec2vector(); return 0; } void array2eigenMat() { cout << "-------------------------- array2eigenMat --------------------------" << endl; int array[9]; for (int i = 0; i < 9; ++i) array[i] = i; cout << "array = [ "; for (int i = 0; i < 9; ++i) cout << array[i] << " "; cout << "]" << endl; cout << "colMajor matrix = \n" << Map<Matrix3i>(array) << endl; // map a contiguous array as a column-major matrix cout << "rowMajor matrix = \n" << Map<Matrix<int, 3, 3, RowMajor>>(array) << endl; // map a contiguous array as a row-major matrix cout << "stride matrix = \n" << Map<MatrixXi, 0, OuterStride<>>(array, 3, 3, OuterStride<>(2)) << endl; //mapping an array while specifying an outer stride. Here, since we're mapping as a column-major matrix, // 'outer stride' means the pointer increment between two consecutive columns Map<MatrixXi> eigMat1(array, 3, 3); MatrixXi eigMat2 = Map<MatrixXi>(array, 3, 3); array[0] = 9; cout << "eigMat1 matrix = \n"; cout << eigMat1 << endl; cout << "eigMat2 matrix = \n"; cout << eigMat2 << endl; cout << "---------------------------------------------------------------------" << endl; } void eigenMat2array() { cout << "-------------------------- eigenMat2array --------------------------" << endl; Matrix3d eigMat; eigMat << 1, 2, 3, 4, 5, 6, 7, 8, 9; cout << "init eigMat = \n"; cout << eigMat << endl; double* eigMatptr = eigMat.data(); cout << "array = [ "; for (int i = 0; i < 9; ++i) cout << eigMatptr[i] << " "; cout << "]" << endl; eigMat(0, 0) = 9; cout << "array = [ "; for (int i = 0; i < 9; ++i) cout << eigMatptr[i] << " "; cout << "]" << endl; double *eigMatptrnew = new double[eigMat.size()]; Map<MatrixXd>(eigMatptrnew, eigMat.rows(), eigMat.cols()) = eigMat; eigMat(2, 2) = 0; cout << "init matrix = \n"; cout << eigMat << endl; cout << "array = [ "; for (int i = 0; i < 9; ++i) cout << eigMatptr[i] << " "; cout << "]" << endl; cout << "---------------------------------------------------------------------" << endl; } void array2eigenVec() { cout << "-------------------------- array2eigenVec --------------------------" << endl; int array[9]; for (int i = 0; i < 9; ++i) array[i] = i; cout << "data array = [ "; for (int i = 0; i < 9; ++i) cout << array[i] << " "; cout << "]" << endl; Map<VectorXi> eigVec(array, 5); cout << "eigen vector transpose = " << eigVec.transpose() << endl; cout << "stride vector transpose = " << Map<VectorXi, 0, InnerStride<2> >(array, 4).transpose() << endl; // map an array as a vector, specifying an inner stride, that is, the pointer increment between two consecutive coefficients array[0] = 9; cout << "eigen vector transpose = " << eigVec.transpose() << endl; cout << "stride vector transpose = " << Map<VectorXi, 0, InnerStride<2> >(array, 4).transpose() << endl; cout << "---------------------------------------------------------------------" << endl; } void eigenVec2array() { cout << "-------------------------- eigenVec2array --------------------------" << endl; VectorXf eigvec(5); eigvec << 0, 1, 2, 3, 4; cout << "eigen vector transpose = " << eigvec.transpose() << endl; float *array = new float; array = eigvec.data(); cout << "data array = [ "; for (int i = 0; i < eigvec.size(); ++i) cout << array[i] << " "; cout << "]" << endl; eigvec(0) = 9; cout << "data array = [ "; for (int i = 0; i < eigvec.size(); ++i) cout << array[i] << " "; cout << "]" << endl; array[0] = 5; cout << "eigen vector transpose = " << eigvec.transpose() << endl; cout << "---------------------------------------------------------------------" << endl; } void vector2eigenMat() { cout << "-------------------------- vector2eigenMat --------------------------" << endl; vector<int> stdvec{ 1, 2, 3, 4, 5, 6, 7, 8, 9 }; Map<Matrix<int, 3, 3, RowMajor>> eigMat1(stdvec.data()); MatrixXi eigMat2 = Map<Matrix<int, 3, 3, RowMajor>>(stdvec.data()); cout << "eigMat1 matrix = \n"; cout << eigMat1 << endl; cout << "eigMat2 matrix = \n"; cout << eigMat2 << endl; stdvec[0] = 9; cout << "eigMat1 matrix = \n"; cout << eigMat1 << endl; cout << "eigMat2 matrix = \n"; cout << eigMat2 << endl; cout << "---------------------------------------------------------------------" << endl; } void eigenMat2vector() { cout << "-------------------------- eigenMat2vector --------------------------" << endl; Matrix3d eigMatCol; eigMatCol << 1, 2, 3, 4, 5, 6, 7, 8, 9; cout << "eigen matrix col = \n"; cout << eigMatCol << endl; vector<double> stdvec1(eigMatCol.data(), eigMatCol.data() + eigMatCol.size()); cout << "std vector1 = ["; for (int i = 0; i < stdvec1.size(); ++i) cout << stdvec1[i] << " "; cout << "]" << endl; Matrix<double, 3, 3, RowMajor> eigMatRow = eigMatCol; cout << "eigen matrix row = \n"; cout << eigMatCol << endl; vector<double> stdvec2(eigMatRow.data(), eigMatRow.data() + eigMatRow.size()); cout << "std vector2 = ["; for (int i = 0; i < stdvec2.size(); ++i) cout << stdvec2[i] << " "; cout << "]" << endl; cout << "---------------------------------------------------------------------" << endl; } void vector2eigenVec() { cout << "-------------------------- vector2eigenVec --------------------------" << endl; vector<int> stdvec{ 1, 2, 3, 4, 5 }; cout << "std vector = ["; for (int i = 0; i < stdvec.size(); ++i) cout << stdvec[i] << " "; cout << "]" << endl; Map<VectorXi> eigVec1(stdvec.data(), stdvec.size()); VectorXi eigVec2 = Map<VectorXi>(stdvec.data(), stdvec.size()); cout << "eigen vector1 transpose = " << eigVec1.transpose() << endl; cout << "eigen vector2 transpose = " << eigVec2.transpose() << endl; cout << "stride vector transpose = " << Map<VectorXi, 0, InnerStride<2> >(stdvec.data(), 2).transpose() << endl; stdvec[0] = 9; cout << "eigen vector1 transpose = " << eigVec1.transpose() << endl; cout << "eigen vector2 transpose = " << eigVec2.transpose() << endl; cout << "stride vector transpose = " << Map<VectorXi, 0, InnerStride<2> >(stdvec.data(), 2).transpose() << endl; cout << "---------------------------------------------------------------------" << endl; } void eigenVec2vector() { cout << "-------------------------- eigenVec2vector --------------------------" << endl; VectorXf eigvec(5); eigvec << 0, 1, 2, 3, 4; cout << "eigen vector transpose = " << eigvec.transpose() << endl; vector<float> stdvec(eigvec.data(), eigvec.data() + eigvec.size()); cout << "std vector = ["; for (int i = 0; i < stdvec.size(); ++i) cout << stdvec[i] << " "; cout << "]" << endl; eigvec(0) = 5; cout << "std vector = ["; for (int i = 0; i < stdvec.size(); ++i) cout << stdvec[i] << " "; cout << "]" << endl; cout << "---------------------------------------------------------------------" << endl; }
程序运行结果
4. 参考
1. Eigen::Map
2. Eigen quick reference guide
3. Vlad's Blog
