alamb commented on code in PR #5798:
URL: https://github.com/apache/arrow-rs/pull/5798#discussion_r1613557809
##########
arrow-array/src/array/primitive_array.rs:
##########
@@ -766,23 +791,43 @@ impl<T: ArrowPrimitiveType> PrimitiveArray<T> {
PrimitiveArray::new(buffer.into(), nulls)
}
- /// Applies an unary and infallible function to a mutable primitive array.
- /// Mutable primitive array means that the buffer is not shared with other
arrays.
- /// As a result, this mutates the buffer directly without allocating new
buffer.
+ /// Applies a unary and infallible function to the array in place if
possible.
+ ///
+ /// # Buffer Reuse
+ ///
+ /// If the underlying buffers are not shared with other arrays, mutates
the
+ /// underlying buffer in place, without allocating.
+ ///
+ /// # Null Handling
///
- /// # Implementation
+ /// See [`Self::unary`] for more information on null handling.
///
- /// This will apply the function for all values, including those on null
slots.
- /// This implies that the operation must be infallible for any value of
the corresponding type
- /// or this function may panic.
/// # Example
+ ///
/// ```rust
/// # use arrow_array::{Int32Array, types::Int32Type};
- /// # fn main() {
/// let array = Int32Array::from(vec![Some(5), Some(7), None]);
+ /// // Apply x*2+1 to the data in place, no allocations
+ /// let c = array.unary_mut(|x| x * 2 + 1).unwrap();
+ /// assert_eq!(c, Int32Array::from(vec![Some(11), Some(15), None]));
+ /// ```
+ ///
+ /// # Example: modify [`ArrayRef`] in place, if not shared
+ ///
+ /// It is also possible to modify an [`ArrayRef`] if there are no other
+ /// references to the underlying buffer.
+ ///
+ /// ```rust
+ /// # use std::sync::Arc;
+ /// # use arrow_array::{Array, ArrayRef, Int32Array, PrimitiveArray,
types::Int32Type};
+ /// # let array: ArrayRef = Arc::new(Int32Array::from(vec![Some(5),
Some(7), None]));
+ /// // Convert to Int32Array (panic's if array.data_type is not Int32)
+ /// let array = PrimitiveArray::<Int32Type>::from(array.into_data());
+ /// // Apply x*2+1 to the data in place, no allocations if
+ /// // there are no other references to the underlying buffer
+ /// // will create a new buffer if there are references.
Review Comment:
Good call, will fix
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