Changed from_pairs to from_map for SparseVector

Author: ankane

src/sparsevec.rs

@@ -35,12 +35,15 @@ impl SparseVector {
         }
     }
 
-    /// Creates a sparse vector from `(index, value)` pairs.
-    pub fn from_pairs<I: IntoIterator<Item = (i32, f32)>>(pairs: I, dim: usize) -> SparseVector {
-        let mut elements: Vec<(i32, f32)> = pairs.into_iter().filter(|v| v.1 != 0.0).collect();
-        elements.sort_by_key(|v| v.0);
-        let indices: Vec<i32> = elements.iter().map(|v| v.0).collect();
-        let values: Vec<f32> = elements.iter().map(|v| v.1).collect();
+    /// Creates a sparse vector from a map of non-zero elements.
+    pub fn from_map<'a, I: IntoIterator<Item = (&'a i32, &'a f32)>>(
+        map: I,
+        dim: usize,
+    ) -> SparseVector {
+        let mut elements: Vec<(&i32, &f32)> = map.into_iter().filter(|v| *v.1 != 0.0).collect();
+        elements.sort_by_key(|v| *v.0);
+        let indices: Vec<i32> = elements.iter().map(|v| *v.0).collect();
+        let values: Vec<f32> = elements.iter().map(|v| *v.1).collect();
 
         SparseVector {
             dim,
@@ -107,7 +110,7 @@ impl SparseVector {
 #[cfg(test)]
 mod tests {
     use crate::SparseVector;
-    use std::collections::HashMap;
+    use std::collections::{BTreeMap, HashMap};
 
     #[test]
     fn test_from_dense() {
@@ -119,19 +122,22 @@ mod tests {
     }
 
     #[test]
-    fn test_from_pairs_map() {
-        let pairs = HashMap::from([(0, 1.0), (2, 2.0), (4, 3.0)]);
-        let vec = SparseVector::from_pairs(pairs, 6);
+    fn test_from_hash_map() {
+        let map = HashMap::from([(0, 1.0), (2, 2.0), (4, 3.0)]);
+        let vec = SparseVector::from_map(&map, 6);
         assert_eq!(vec![1.0, 0.0, 2.0, 0.0, 3.0, 0.0], vec.to_vec());
         assert_eq!(6, vec.dimensions());
         assert_eq!(&[0, 2, 4], vec.indices());
         assert_eq!(&[1.0, 2.0, 3.0], vec.values());
     }
 
     #[test]
-    fn test_from_pairs_vec() {
-        let pairs = vec![(0, 1.0), (2, 2.0), (4, 3.0)];
-        let vec = SparseVector::from_pairs(pairs, 6);
+    fn test_from_btree_map() {
+        let map = BTreeMap::from([(0, 1.0), (2, 2.0), (4, 3.0)]);
+        let vec = SparseVector::from_map(&map, 6);
         assert_eq!(vec![1.0, 0.0, 2.0, 0.0, 3.0, 0.0], vec.to_vec());
+        assert_eq!(6, vec.dimensions());
+        assert_eq!(&[0, 2, 4], vec.indices());
+        assert_eq!(&[1.0, 2.0, 3.0], vec.values());
     }
 }