export to file directly; add a new trait for export

nalgebra-sparse/src/io/matrix_market.rs

@@ -1,10 +1,9 @@
 //! Implementation of matrix market io code.
 //!
 //! See the [website](https://math.nist.gov/MatrixMarket/formats.html) or the [paper](https://www.researchgate.net/publication/2630533_The_Matrix_Market_Exchange_Formats_Initial_Design) for more details about matrix market.
-use crate::CooMatrix;
 use crate::SparseFormatError;
 use crate::SparseFormatErrorKind;
-use matrixcompare_core::SparseAccess;
+use crate::{CooMatrix, CscMatrix, CsrMatrix};
 use nalgebra::Complex;
 use pest::iterators::Pairs;
 use pest::Parser;
@@ -513,6 +512,17 @@ mod internal {
         /// Convert the data to string
         fn to_matrixmarket_string(&self) -> String;
     }
+
+    pub trait SupportedMatrixMarketExport<T: SupportedMatrixMarketScalar> {
+        /// iterate over triplets
+        fn triplet_iter(&self) -> Box<dyn Iterator<Item = (usize, usize, &T)> + '_>;
+        /// number of rows
+        fn nrows(&self) -> usize;
+        /// number of columns
+        fn ncols(&self) -> usize;
+        /// number of non-zeros
+        fn nnz(&self) -> usize;
+    }
 }
 
 /// A marker trait for supported matrix market scalars.
@@ -754,6 +764,46 @@ mm_complex_impl!(f64);
 
 mm_pattern_impl!(());
 
+/// A marker trait for supported sparse matrix types.
+///
+/// This is a sealed trait; it cannot be implemented by external crates. This is done in order to prevent leaking
+/// some of the implementation details we currently rely on. We may relax this restriction in the future.
+pub trait MatrixMarketExport<T: MatrixMarketScalar>:
+    internal::SupportedMatrixMarketExport<T>
+{
+}
+
+macro_rules! mm_matrix_impl {
+    ($T_MATRIX:ty) => {
+        impl<T: MatrixMarketScalar> MatrixMarketExport<T> for $T_MATRIX {}
+
+        impl<T: internal::SupportedMatrixMarketScalar> internal::SupportedMatrixMarketExport<T>
+            for $T_MATRIX
+        {
+            #[inline]
+            fn triplet_iter(&self) -> Box<dyn Iterator<Item = (usize, usize, &T)> + '_> {
+                Box::new(self.triplet_iter())
+            }
+            #[inline]
+            fn nrows(&self) -> usize {
+                self.nrows()
+            }
+            #[inline]
+            fn ncols(&self) -> usize {
+                self.ncols()
+            }
+            #[inline]
+            fn nnz(&self) -> usize {
+                self.nnz()
+            }
+        }
+    };
+}
+
+mm_matrix_impl!(CooMatrix<T>);
+mm_matrix_impl!(CsrMatrix<T>);
+mm_matrix_impl!(CscMatrix<T>);
+
 #[derive(Parser)]
 #[grammar = "io/matrix_market.pest"]
 struct MatrixMarketParser;
@@ -1391,23 +1441,29 @@ fn next_dense_coordinate(
 /// let generated_matrixmarket = load_coo_from_matrix_market_str::<i32>(&generated_matrixmarket_string).unwrap();
 /// assert_matrix_eq!(matrix,generated_matrixmarket);
 /// ```
-pub fn write_to_matrix_market_str<T: MatrixMarketScalar, S: SparseAccess<T>>(
+pub fn write_to_matrix_market_str<T: MatrixMarketScalar, S: MatrixMarketExport<T>>(
     sparse_matrix: &S,
 ) -> String {
     let mut matrixmarket_string = String::new();
+
     // write header
     matrixmarket_string.push_str("%%matrixmarket matrix coordinate ");
     matrixmarket_string.push_str(T::typename());
-    matrixmarket_string.push_str(" general\n% matrixmarket file generated by nalgebra-sparse.\n");
+    matrixmarket_string.push_str(" general\n");
+
+    //write comment
+    matrixmarket_string.push_str("% matrixmarket file generated by nalgebra-sparse.\n");
+
     // write shape information
-    matrixmarket_string.push_str(&sparse_matrix.rows().to_string());
+    matrixmarket_string.push_str(&sparse_matrix.nrows().to_string());
     matrixmarket_string.push(' ');
-    matrixmarket_string.push_str(&sparse_matrix.cols().to_string());
+    matrixmarket_string.push_str(&sparse_matrix.ncols().to_string());
     matrixmarket_string.push(' ');
     matrixmarket_string.push_str(&sparse_matrix.nnz().to_string());
     matrixmarket_string.push('\n');
 
-    for (r, c, d) in sparse_matrix.fetch_triplets() {
+    //write triplets
+    for (r, c, d) in sparse_matrix.triplet_iter() {
         matrixmarket_string.push_str(&(r + 1).to_string());
         matrixmarket_string.push_str("  ");
         matrixmarket_string.push_str(&(c + 1).to_string());
@@ -1415,7 +1471,6 @@ pub fn write_to_matrix_market_str<T: MatrixMarketScalar, S: SparseAccess<T>>(
         matrixmarket_string.push_str(&d.to_matrixmarket_string());
         matrixmarket_string.push_str("\n");
     }
-
     matrixmarket_string
 }
 
@@ -1445,12 +1500,46 @@ pub fn write_to_matrix_market_str<T: MatrixMarketScalar, S: SparseAccess<T>>(
 /// // do something
 /// }
 /// ```
-pub fn write_to_matrix_market_file<T: MatrixMarketScalar, S: SparseAccess<T>, P: AsRef<Path>>(
-    matrix: &S,
+pub fn write_to_matrix_market_file<
+    T: MatrixMarketScalar,
+    S: MatrixMarketExport<T>,
+    P: AsRef<Path>,
+>(
+    sparse_matrix: &S,
     path: P,
 ) -> Result<(), MatrixMarketError> {
-    let matrixmarket_string = write_to_matrix_market_str(matrix);
+    // The code is basically the same as write_to_matrix_market_str, but write the matrix into file instead.
     let mut file = File::create(path)?;
-    write!(file, "{}", matrixmarket_string)?;
+
+    // write header
+    write!(
+        file,
+        "%%matrixmarket matrix coordinate  {} general\n",
+        T::typename()
+    )?;
+
+    // write comments
+    write!(file, "% matrixmarket file generated by nalgebra-sparse.\n",)?;
+
+    // write shape information
+    write!(
+        file,
+        "{} {} {}\n",
+        sparse_matrix.nrows(),
+        sparse_matrix.ncols(),
+        sparse_matrix.nnz()
+    )?;
+
+    // write triplets
+    for (r, c, d) in sparse_matrix.triplet_iter() {
+        write!(
+            file,
+            "{}  {}  {}\n",
+            r + 1,
+            c + 1,
+            d.to_matrixmarket_string()
+        )?;
+    }
+
     Ok(())
 }

nalgebra-sparse/src/io/mod.rs

@@ -33,6 +33,7 @@
 
 pub use self::matrix_market::{
     load_coo_from_matrix_market_file, load_coo_from_matrix_market_str, write_to_matrix_market_file,
-    write_to_matrix_market_str, MatrixMarketError, MatrixMarketErrorKind, MatrixMarketScalar,
+    write_to_matrix_market_str, MatrixMarketError, MatrixMarketErrorKind, MatrixMarketExport,
+    MatrixMarketScalar,
 };
 mod matrix_market;