Adds DecisionTree algorithm

src/linalg/mod.rs

@@ -18,6 +18,10 @@ pub trait Matrix: Clone + Debug {
 
     fn get(&self, row: usize, col: usize) -> f64; 
 
+    fn get_row_as_vec(&self, row: usize) -> Vec<f64>;
+
+    fn get_col_as_vec(&self, col: usize) -> Vec<f64>;
+
     fn set(&mut self, row: usize, col: usize, x: f64);
 
     fn qr_solve_mut(&mut self, b: Self) -> Self;

src/linalg/naive/dense_matrix.rs

@@ -135,6 +135,22 @@ impl Matrix for DenseMatrix {
         self.values[col*self.nrows + row]
     }
 
+    fn get_row_as_vec(&self, row: usize) -> Vec<f64>{
+        let mut result = vec![0f64; self.ncols];
+        for c in 0..self.ncols {
+            result[c] = self.get(row, c);
+        }
+        result
+    }
+
+    fn get_col_as_vec(&self, col: usize) -> Vec<f64>{
+        let mut result = vec![0f64; self.nrows];
+        for r in 0..self.nrows {
+            result[r] = self.get(r, col);
+        }        
+        result
+    }
+
     fn set(&mut self, row: usize, col: usize, x: f64) {
         self.values[col*self.nrows + row] = x;        
     }

src/linalg/ndarray_bindings.rs

@@ -28,6 +28,14 @@ impl Matrix for ArrayBase<OwnedRepr<f64>, Ix2>
         self[[row, col]]
     }
 
+    fn get_row_as_vec(&self, row: usize) -> Vec<f64> {
+        self.row(row).to_vec()
+    }
+
+    fn get_col_as_vec(&self, col: usize) -> Vec<f64> {
+        self.column(col).to_vec()
+    }
+
     fn set(&mut self, row: usize, col: usize, x: f64) {
         self[[row, col]] = x;
     }
@@ -509,4 +517,18 @@ mod tests {
         assert_eq!(res.len(), 7);
         assert_eq!(res, vec![-7., -6., -2., 1., 2., 3., 4.]);
     }
+
+    #[test]
+    fn get_row_as_vector(){
+        let a = arr2(&[[1., 2., 3.], [4., 5., 6.], [7., 8., 9.]]);  
+        let res = a.get_row_as_vec(1);
+        assert_eq!(res, vec![4., 5., 6.]);        
+    }
+
+    #[test]
+    fn get_col_as_vector(){
+        let a = arr2(&[[1., 2., 3.], [4., 5., 6.], [7., 8., 9.]]);  
+        let res = a.get_col_as_vec(1);
+        assert_eq!(res, vec![2., 5., 8.]);        
+    }
 }