alamb commented on code in PR #7993:
URL: https://github.com/apache/arrow-datafusion/pull/7993#discussion_r1379196635
##########
datafusion/common/src/utils.rs:
##########
@@ -348,6 +349,47 @@ pub fn wrap_into_list_array(arr: ArrayRef) -> ListArray {
)
}
+/// Wrap arrays into a single element `ListArray`.
+///
+/// Example:
+/// ```
+/// use arrow::array::{Int32Array, ListArray, ArrayRef};
+/// use arrow::datatypes::{Int32Type, Field};
+/// use std::sync::Arc;
+///
+/// let arr1 = Arc::new(Int32Array::from(vec![1, 2, 3])) as ArrayRef;
+/// let arr2 = Arc::new(Int32Array::from(vec![4, 5, 6])) as ArrayRef;
+///
+/// let list_arr = datafusion_common::utils::arrays_into_list_array([arr1,
arr2]).unwrap();
+///
+/// let expected = ListArray::from_iter_primitive::<Int32Type, _, _>(
+/// vec![
+/// Some(vec![Some(1), Some(2), Some(3)]),
+/// Some(vec![Some(4), Some(5), Some(6)]),
+/// ]
+/// );
+///
+/// assert_eq!(list_arr, expected);
+pub fn arrays_into_list_array(
+ arr: impl IntoIterator<Item = ArrayRef>,
+) -> Result<ListArray> {
+ let arr = arr.into_iter().collect::<Vec<_>>();
+ if arr.is_empty() {
+ return _internal_err!("Cannot wrap empty array into list array");
+ }
+
+ let lens = arr.iter().map(|x| x.len()).collect::<Vec<_>>();
+ // Assume data type is consistent
+ let data_type = arr[0].data_type().to_owned();
+ let values = arr.iter().map(|x| x.as_ref()).collect::<Vec<_>>();
+ Ok(ListArray::new(
+ Arc::new(Field::new("item", data_type, true)),
+ OffsetBuffer::from_lengths(lens),
+ arrow::compute::concat(values.as_slice())?,
Review Comment:
I double checked that concat doesn't do anything with a single input:
https://github.com/apache/arrow-rs/blob/78735002d99eb0212166924948f95554c4ac2866/arrow-select/src/concat.rs#L116-L118
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