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Posted to commits@arrow.apache.org by al...@apache.org on 2021/12/23 18:21:09 UTC
[arrow-rs] branch active_release updated: support cast decimal to decimal (#1084) (#1093)
This is an automated email from the ASF dual-hosted git repository.
alamb pushed a commit to branch active_release
in repository https://gitbox.apache.org/repos/asf/arrow-rs.git
The following commit(s) were added to refs/heads/active_release by this push:
new 092fc64 support cast decimal to decimal (#1084) (#1093)
092fc64 is described below
commit 092fc64bbb019244887ebd0d9c9a2d3e3a9aebc0
Author: Andrew Lamb <an...@nerdnetworks.org>
AuthorDate: Thu Dec 23 13:21:04 2021 -0500
support cast decimal to decimal (#1084) (#1093)
* support cast decimal to decimal
* add test case
* remove meaningless code
Co-authored-by: Kun Liu <li...@apache.org>
---
arrow/src/compute/kernels/cast.rs | 68 ++++++++++++++++++++++++++++++++++++++-
1 file changed, 67 insertions(+), 1 deletion(-)
diff --git a/arrow/src/compute/kernels/cast.rs b/arrow/src/compute/kernels/cast.rs
index 42e5e7f..d302bdd 100644
--- a/arrow/src/compute/kernels/cast.rs
+++ b/arrow/src/compute/kernels/cast.rs
@@ -69,7 +69,8 @@ pub fn can_cast_types(from_type: &DataType, to_type: &DataType) -> bool {
match (from_type, to_type) {
// TODO UTF8/unsigned numeric to decimal
- // TODO decimal to decimal type
+ // cast one decimal type to another decimal type
+ (Decimal(_, _), Decimal(_, _)) => true,
// signed numeric to decimal
(Int8 | Int16 | Int32 | Int64 | Float32 | Float64, Decimal(_, _)) |
// decimal to signed numeric
@@ -435,6 +436,7 @@ pub fn cast_with_options(
return Ok(array.clone());
}
match (from_type, to_type) {
+ (Decimal(_, s1), Decimal(p2, s2)) => cast_decimal_to_decimal(array, s1, p2, s2),
(Decimal(_, scale), _) => {
// cast decimal to other type
match to_type {
@@ -1203,6 +1205,42 @@ const MILLISECONDS_IN_DAY: i64 = SECONDS_IN_DAY * MILLISECONDS;
/// Number of days between 0001-01-01 and 1970-01-01
const EPOCH_DAYS_FROM_CE: i32 = 719_163;
+/// Cast one type of decimal array to another type of decimal array
+fn cast_decimal_to_decimal(
+ array: &ArrayRef,
+ input_scale: &usize,
+ output_precision: &usize,
+ output_scale: &usize,
+) -> Result<ArrayRef> {
+ let mut decimal_builder =
+ DecimalBuilder::new(array.len(), *output_precision, *output_scale);
+ let array = array.as_any().downcast_ref::<DecimalArray>().unwrap();
+ if input_scale > output_scale {
+ // For example, input_scale is 4 and output_scale is 3;
+ // Original value is 11234_i128, and will be cast to 1123_i128.
+ let div = 10_i128.pow((input_scale - output_scale) as u32);
+ for i in 0..array.len() {
+ if array.is_null(i) {
+ decimal_builder.append_null()?;
+ } else {
+ decimal_builder.append_value(array.value(i) / div)?;
+ }
+ }
+ } else {
+ // For example, input_scale is 3 and output_scale is 4;
+ // Original value is 1123_i128, and will be cast to 11230_i128.
+ let mul = 10_i128.pow((output_scale - input_scale) as u32);
+ for i in 0..array.len() {
+ if array.is_null(i) {
+ decimal_builder.append_null()?;
+ } else {
+ decimal_builder.append_value(array.value(i) * mul)?;
+ }
+ }
+ }
+ Ok(Arc::new(decimal_builder.finish()))
+}
+
/// Cast an array by changing its array_data type to the desired type
///
/// Arrays should have the same primitive data type, otherwise this should fail.
@@ -2100,6 +2138,34 @@ mod tests {
}
#[test]
+ fn test_cast_decimal_to_decimal() {
+ let input_type = DataType::Decimal(20, 3);
+ let output_type = DataType::Decimal(20, 4);
+ assert!(can_cast_types(&input_type, &output_type));
+ let array = vec![Some(1123456), Some(2123456), Some(3123456), None];
+ let input_decimal_array = create_decimal_array(&array, 20, 3).unwrap();
+ let array = Arc::new(input_decimal_array) as ArrayRef;
+ generate_cast_test_case!(
+ &array,
+ DecimalArray,
+ &output_type,
+ vec![
+ Some(11234560_i128),
+ Some(21234560_i128),
+ Some(31234560_i128),
+ None
+ ]
+ );
+ // negative test
+ let array = vec![Some(123456), None];
+ let input_decimal_array = create_decimal_array(&array, 10, 0).unwrap();
+ let array = Arc::new(input_decimal_array) as ArrayRef;
+ let result = cast(&array, &DataType::Decimal(2, 2));
+ assert!(result.is_err());
+ assert_eq!("Invalid argument error: The value of 12345600 i128 is not compatible with Decimal(2,2)".to_string(), result.unwrap_err().to_string());
+ }
+
+ #[test]
fn test_cast_decimal_to_numeric() {
let decimal_type = DataType::Decimal(38, 2);
// negative test