Add useful compat function which emulates Matrix::MakeColumnVector() functionality (albeit slowly)

fastlib/branches/fastlib-armadillo/fastlib/base/arma_compat.cc

@@ -12,7 +12,7 @@
  *
  * This wasn't written to be fast or efficient.
  */
-void arma_compat::armaToMatrix(const arma::mat &mat, Matrix &mg) {
+void arma_compat::armaToMatrix(const arma::mat& mat, Matrix& mg) {
   // initialize our matrix correctly
   mg.Init(mat.n_rows, mat.n_cols);
 
@@ -29,7 +29,7 @@ void arma_compat::armaToMatrix(const arma::mat &mat, Matrix &mg) {
  *
  * This wasn't written to be fast or efficient.
  */
-void arma_compat::matrixToArma(const Matrix &gm, arma::mat &mat) {
+void arma_compat::matrixToArma(const Matrix& gm, arma::mat& mat) {
   // initialize our matrix to the correct size
   mat.set_size(gm.n_rows(), gm.n_cols());
 
@@ -40,3 +40,17 @@ void arma_compat::matrixToArma(const Matrix &gm, arma::mat &mat) {
     }
   }
 }
+
+/***
+ * Write the selected column of the matrix into the uninitialized Vector.
+ *
+ * This wasn't written to be fast or efficient.
+ */
+void arma_compat::armaColVector(const arma::mat& mat, int col, Vector& v) {
+  // initialize our vector to the correct size
+  v.Init(mat.n_rows);
+
+  // copy elementwise.  this is slow as hell
+  for(int r = 0; r < mat.n_rows; r++)
+    v[r] = mat(r, col);
+}

fastlib/branches/fastlib-armadillo/fastlib/base/arma_compat.h

@@ -18,6 +18,8 @@ namespace arma_compat {
   void armaToMatrix(const arma::mat &mat, Matrix &mg);
   void matrixToArma(const Matrix &gm, arma::mat &mat);
 
+  // write a column into an uninitialized vector
+  void armaColVector(const arma::mat &mat, int col, Vector &v);
 }
 
 #endif /* ARMA_COMPAT_H */