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new 02573e9 Add Rust Docs examples for UnionArray (#1241)
02573e9 is described below
commit 02573e90b622d0ca2b1694d4e8513da638f67f7c
Author: Remzi Yang <[email protected]>
AuthorDate: Fri Jan 28 04:54:21 2022 +0800
Add Rust Docs examples for UnionArray (#1241)
Signed-off-by: remzi <[email protected]>
---
arrow/src/array/array_union.rs | 67 ++++++++++++++++++++++++++++++++++++++++++
1 file changed, 67 insertions(+)
diff --git a/arrow/src/array/array_union.rs b/arrow/src/array/array_union.rs
index 3657729..9c99011 100644
--- a/arrow/src/array/array_union.rs
+++ b/arrow/src/array/array_union.rs
@@ -35,6 +35,73 @@ use std::any::Any;
/// [`UnionBuilder`]can be used to create `UnionArray`'s of primitive types.
`UnionArray`'s of nested
/// types are also supported but not via `UnionBuilder`, see the tests for
examples.
///
+/// # Examples
+/// ## Create a dense UnionArray `[1, 3.2, 34]`
+/// ```
+/// use arrow::buffer::Buffer;
+/// use arrow::datatypes::*;
+/// use std::sync::Arc;
+/// use arrow::array::{Array, Int32Array, Float64Array, UnionArray};
+///
+/// let int_array = Int32Array::from(vec![1, 34]);
+/// let float_array = Float64Array::from(vec![3.2]);
+/// let type_id_buffer = Buffer::from_slice_ref(&[0_i8, 1, 0]);
+/// let value_offsets_buffer = Buffer::from_slice_ref(&[0_i32, 0, 1]);
+///
+/// let children: Vec<(Field, Arc<dyn Array>)> = vec![
+/// (Field::new("A", DataType::Int32, false), Arc::new(int_array)),
+/// (Field::new("B", DataType::Float64, false), Arc::new(float_array)),
+/// ];
+///
+/// let array = UnionArray::try_new(
+/// type_id_buffer,
+/// Some(value_offsets_buffer),
+/// children,
+/// None,
+/// ).unwrap();
+///
+/// let value =
array.value(0).as_any().downcast_ref::<Int32Array>().unwrap().value(0);
+/// assert_eq!(1, value);
+///
+/// let value =
array.value(1).as_any().downcast_ref::<Float64Array>().unwrap().value(0);
+/// assert!(3.2 - value < f64::EPSILON);
+///
+/// let value =
array.value(2).as_any().downcast_ref::<Int32Array>().unwrap().value(0);
+/// assert_eq!(34, value);
+/// ```
+///
+/// ## Create a sparse UnionArray `[1, 3.2, 34]`
+/// ```
+/// use arrow::buffer::Buffer;
+/// use arrow::datatypes::*;
+/// use std::sync::Arc;
+/// use arrow::array::{Array, Int32Array, Float64Array, UnionArray};
+///
+/// let int_array = Int32Array::from(vec![Some(1), None, Some(34)]);
+/// let float_array = Float64Array::from(vec![None, Some(3.2), None]);
+/// let type_id_buffer = Buffer::from_slice_ref(&[0_i8, 1, 0]);
+///
+/// let children: Vec<(Field, Arc<dyn Array>)> = vec![
+/// (Field::new("A", DataType::Int32, false), Arc::new(int_array)),
+/// (Field::new("B", DataType::Float64, false), Arc::new(float_array)),
+/// ];
+///
+/// let array = UnionArray::try_new(
+/// type_id_buffer,
+/// None,
+/// children,
+/// None,
+/// ).unwrap();
+///
+/// let value =
array.value(0).as_any().downcast_ref::<Int32Array>().unwrap().value(0);
+/// assert_eq!(1, value);
+///
+/// let value =
array.value(1).as_any().downcast_ref::<Float64Array>().unwrap().value(0);
+/// assert!(3.2 - value < f64::EPSILON);
+///
+/// let value =
array.value(2).as_any().downcast_ref::<Int32Array>().unwrap().value(0);
+/// assert_eq!(34, value);
+/// ```
pub struct UnionArray {
data: ArrayData,
boxed_fields: Vec<ArrayRef>,
