Impl function to print a matrix in NumPy format

.vscode/settings.json

@@ -98,6 +98,7 @@
     "nroot",
     "nstage",
     "nstep",
+    "numpy",
     "odyad",
     "Oleg",
     "oneapi",

russell_lab/src/matrix/mat_to_numpy.rs

@@ -0,0 +1,75 @@
+use super::Matrix;
+use std::fmt::Write;
+
+/// Generates numpy code with a nested list representing a matrix
+///
+/// When saved to a file, we can execute the numpy script as:
+///
+/// ```text
+/// math < /tmp/russell_lab/the_matrix.m
+/// ```
+///
+/// # Examples
+///
+/// ```
+/// use russell_lab::{mat_to_numpy, Matrix};
+///
+/// fn main() {
+///     #[rustfmt::skip]
+///     let a = Matrix::from(&[
+///         [ 1.0,  2.0],
+///         [-3.0,  4.0],
+///         [ 5.0,  6.0e-10],
+///     ]);
+///
+///     let res = mat_to_numpy("a_matrix", &a);
+///
+///     let correct = "a_matrix = np.array([[1,2],[-3,4],[5,0.0000000006]],dtype=float)";
+///
+///     assert_eq!(res, correct);
+/// }
+/// ```
+pub fn mat_to_numpy(name: &str, a: &Matrix) -> String {
+    let (nrow, ncol) = a.dims();
+    let mut buf = String::new();
+    write!(&mut buf, "{} = np.array([", name).unwrap();
+    for i in 0..nrow {
+        if i > 0 {
+            write!(&mut buf, "],").unwrap();
+        }
+        for j in 0..ncol {
+            if j == 0 {
+                write!(&mut buf, "[").unwrap();
+            } else {
+                write!(&mut buf, ",").unwrap();
+            }
+            let val = a.get(i, j);
+            write!(&mut buf, "{}", val).unwrap();
+        }
+    }
+    write!(&mut buf, "]],dtype=float)").unwrap();
+    buf
+}
+
+////////////////////////////////////////////////////////////////////////////////////////////////////////////////////////
+
+#[cfg(test)]
+mod tests {
+    use super::{mat_to_numpy, Matrix};
+
+    #[test]
+    fn mat_to_numpy_works() {
+        #[rustfmt::skip]
+        let a = Matrix::from(&[
+            [  1.0,  20.0],
+            [  3.01,  4.0],
+            [-55.0,   6.0],
+            [  7.0,   8.0e-10],
+        ]);
+        let res = mat_to_numpy("a_matrix", &a);
+        assert_eq!(
+            res,
+            "a_matrix = np.array([[1,20],[3.01,4],[-55,6],[7,0.0000000008]],dtype=float)"
+        )
+    }
+}

russell_lab/src/matrix/mod.rs

@@ -39,6 +39,7 @@ mod mat_svd;
 mod mat_sym_rank_op;
 mod mat_t_mat_mul;
 mod mat_to_mathematica;
+mod mat_to_numpy;
 mod mat_to_static_array;
 mod mat_update;
 mod mat_write_vismatrix;
@@ -84,6 +85,7 @@ pub use mat_svd::*;
 pub use mat_sym_rank_op::*;
 pub use mat_t_mat_mul::*;
 pub use mat_to_mathematica::*;
+pub use mat_to_numpy::*;
 pub use mat_to_static_array::*;
 pub use mat_update::*;
 pub use mat_write_vismatrix::*;