chore: improve From<Ca> -> Vec

crates/polars-core/src/chunked_array/upstream_traits.rs

@@ -609,13 +609,18 @@ where
     }
 }
 
-/// From trait
-impl<'a> From<&'a StringChunked> for Vec<Option<&'a str>> {
-    fn from(ca: &'a StringChunked) -> Self {
-        ca.into_iter().collect()
+impl<'a, T> From<&'a ChunkedArray<T>> for Vec<Option<T::Physical<'a>>>
+where
+    T: PolarsDataType,
+{
+    fn from(ca: &'a ChunkedArray<T>) -> Self {
+        let mut out = Vec::with_capacity(ca.len());
+        for arr in ca.downcast_iter() {
+            out.extend(arr.iter())
+        }
+        out
     }
 }
-
 impl From<StringChunked> for Vec<Option<String>> {
     fn from(ca: StringChunked) -> Self {
         ca.into_iter()
@@ -624,27 +629,17 @@ impl From<StringChunked> for Vec<Option<String>> {
     }
 }
 
-impl<'a> From<&'a BooleanChunked> for Vec<Option<bool>> {
-    fn from(ca: &'a BooleanChunked) -> Self {
-        ca.into_iter().collect()
-    }
-}
-
 impl From<BooleanChunked> for Vec<Option<bool>> {
     fn from(ca: BooleanChunked) -> Self {
-        ca.into_iter().collect()
-    }
-}
-
-impl<'a, T> From<&'a ChunkedArray<T>> for Vec<Option<T::Native>>
-where
-    T: PolarsNumericType,
-{
-    fn from(ca: &'a ChunkedArray<T>) -> Self {
-        ca.into_iter().collect()
+        let mut out = Vec::with_capacity(ca.len());
+        for arr in ca.downcast_iter() {
+            out.extend(arr.iter())
+        }
+        out
     }
 }
 
+/// From trait
 impl FromParallelIterator<Option<Series>> for ListChunked {
     fn from_par_iter<I>(iter: I) -> Self
     where