Added len function to Matrix

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 0.2.1 (unreleased)
+
+- Added `len` function to `Matrix`
+
 ## 0.2.0 (2021-10-17)
 
 - Added support for Windows

src/matrix.rs

@@ -23,6 +23,10 @@ impl Matrix {
         self.data.push(MfNode { u: row_index, v: column_index, r: value });
     }
 
+    pub fn len(&self) -> usize {
+        self.data.len()
+    }
+
     pub(crate) fn to_problem(&self) -> MfProblem {
         let data = &self.data;
         let m = data.iter().map(|x| x.u).max().unwrap_or(-1) + 1;
@@ -52,4 +56,12 @@ mod tests {
         let mut data = Matrix::with_capacity(1);
         data.push(0, 0, 1.0);
     }
+
+    #[test]
+    fn test_len() {
+        let mut data = Matrix::new();
+        assert_eq!(data.len(), 0);
+        data.push(0, 0, 1.0);
+        assert_eq!(data.len(), 1);
+    }
 }