[GitHub] [arrow] jorgecarleitao commented on a change in pull request #9293: ARROW-11349: [Rust[ Add from_iter_values to create arrays from (non null) values

[GitBox <gi...@apache.org>]

jorgecarleitao commented on a change in pull request #9293:
URL: https://github.com/apache/arrow/pull/9293#discussion_r562853687



##########
File path: rust/arrow/src/array/array_primitive.rs
##########
@@ -94,6 +94,32 @@ impl<T: ArrowPrimitiveType> PrimitiveArray<T> {
         let offset = i + self.offset();
         unsafe { *self.raw_values.as_ptr().add(offset) }
     }
+
+    /// Creates a PrimitiveArray based on an iterator of values without nulls
+    pub fn from_iter_values<I: IntoIterator<Item = T::Native>>(iter: I) -> Self {
+        let iter = iter.into_iter();
+        let (_, data_len) = iter.size_hint();
+        let data_len = data_len.expect("Iterator must be sized"); // panic if no upper bound.
+
+        let mut val_buf = MutableBuffer::new(
+            data_len * mem::size_of::<<T as ArrowPrimitiveType>::Native>(),
+        );
+
+        iter.for_each(|item| {
+            val_buf.push(item);
+        });

Review comment:
       Could we wait for #9235? It introduces a method to extend a `MutableBuffer` out of an iterator of Native types. It will also allow to drop the `.expect("Iterator must be sized")`, since it will be possible to extend it out of unsized iterators.




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