tustvold commented on code in PR #3258:
URL: https://github.com/apache/arrow-rs/pull/3258#discussion_r1038402887
##########
arrow-array/src/array/boolean_array.rs:
##########
@@ -173,6 +174,92 @@ impl BooleanArray {
) -> impl Iterator<Item = Option<bool>> + 'a {
indexes.map(|opt_index| opt_index.map(|index|
self.value_unchecked(index)))
}
+
+ /// Create a [`BooleanArray`] by evaluating the operation for
+ /// each element of the provided array
+ ///
+ /// ```
+ /// # use arrow_array::{BooleanArray, Int32Array};
+ ///
+ /// let array = Int32Array::from(vec![1, 2, 3, 4, 5]);
+ /// let r = BooleanArray::from_unary(&array, |x| x > 2);
+ /// assert_eq!(&r, &BooleanArray::from(vec![false, false, true, true,
true]));
+ /// ```
+ pub fn from_unary<T: ArrayAccessor, F>(left: T, mut op: F) -> Self
+ where
+ F: FnMut(T::Item) -> bool,
+ {
+ let null_bit_buffer = left
+ .data()
+ .null_buffer()
+ .map(|b| b.bit_slice(left.offset(), left.len()));
+
+ let buffer = MutableBuffer::collect_bool(left.len(), |i| unsafe {
+ // SAFETY: i in range 0..len
+ op(left.value_unchecked(i))
+ });
+
+ let data = unsafe {
+ ArrayData::new_unchecked(
+ DataType::Boolean,
+ left.len(),
+ None,
+ null_bit_buffer,
+ 0,
+ vec![Buffer::from(buffer)],
+ vec![],
+ )
+ };
+ Self::from(data)
+ }
+
+ /// Create a [`BooleanArray`] by evaluating the binary operation for
+ /// each element of the provided arrays
+ ///
+ /// ```
+ /// # use arrow_array::{BooleanArray, Int32Array};
+ ///
+ /// let a = Int32Array::from(vec![1, 2, 3, 4, 5]);
+ /// let b = Int32Array::from(vec![1, 2, 0, 2, 5]);
+ /// let r = BooleanArray::from_binary(&a, &b, |a, b| a == b).unwrap();
+ /// assert_eq!(&r, &BooleanArray::from(vec![true, true, false, false,
true]));
+ /// ```
+ ///
+ /// # Panics
+ ///
+ /// This function panics if left and right are not the same length
Review Comment:
I specifically want this to be infallible, because I want a future
`try_from_binary` to be able to return a user-provided error, instead of
bundling it up in `ArrowError`.
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