Add try_from_triplets_iter

Calls `try_from_triplets` for now, and is mentioned in the documentation.

nalgebra-sparse/src/coo.rs

@@ -160,6 +160,25 @@ impl<T> CooMatrix<T> {
         }
     }
 
+    /// Try to construct a COO matrix from the given dimensions and a finite iterator of
+    /// (i, j, v) triplets.
+    ///
+    /// Returns an error if either row or column indices contain indices out of bounds.
+    /// Note that the COO format inherently supports duplicate entries, but they are not
+    /// eagerly summed.
+    ///
+    /// Implementation note:
+    /// Calls try_from_triplets so each value is scanned twice.
+    pub fn try_from_triplets_iter(
+        nrows: usize,
+        ncols: usize,
+        triplets: impl IntoIterator<Item = (usize, usize, T)>,
+    ) -> Result<Self, SparseFormatError> {
+        let (row_indices, (col_indices, values)) =
+            triplets.into_iter().map(|(r, c, v)| (r, (c, v))).unzip();
+        Self::try_from_triplets(nrows, ncols, row_indices, col_indices, values)
+    }
+
     /// An iterator over triplets (i, j, v).
     // TODO: Consider giving the iterator a concrete type instead of impl trait...?
     pub fn triplet_iter(&self) -> impl Iterator<Item = (usize, usize, &T)> {