[GitHub] [arrow-rs] Dandandan commented on a change in pull request #275: add nullity function and some unit tests

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

Dandandan commented on a change in pull request #275:
URL: https://github.com/apache/arrow-rs/pull/275#discussion_r629333194



##########
File path: arrow/src/compute/kernels/arity.rs
##########
@@ -72,3 +72,40 @@ where
     let data = into_primitive_array_data::<_, O>(array, buffer);
     PrimitiveArray::<O>::from(data)
 }
+
+/// Applies a nullary and infalible function to generate a primitive array.
+/// You should use this instead of the vectorized version when each generated value is different.
+pub fn nullary<F, O>(size: usize, op: F) -> PrimitiveArray<O>
+where
+    O: ArrowPrimitiveType,
+    F: Fn() -> O::Native,
+{
+    let values = (0..size).map(|_| op());

Review comment:
       This could use `std::iter::repeat`




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