[GitHub] [arrow-rs] liukun4515 commented on a change in pull request #1223: `DecimalArray` API ergonomics: add iter(), create from iter(), change precision / scale

[GitBox <gi...@apache.org>]

liukun4515 commented on a change in pull request #1223:
URL: https://github.com/apache/arrow-rs/pull/1223#discussion_r790370190



##########
File path: arrow/src/array/array_binary.rs
##########
@@ -816,13 +827,80 @@ impl DecimalArray {
         let array_data = unsafe { builder.build_unchecked() };
         Self::from(array_data)
     }
+
+    /// Creates a [DecimalArray] with default precision and scale,
+    /// based on an iterator of `i128` values without nulls
+    pub fn from_iter_values<I: IntoIterator<Item = i128>>(iter: I) -> Self {
+        let val_buf: Buffer = iter.into_iter().collect();
+        let data = unsafe {
+            ArrayData::new_unchecked(
+                Self::default_type(),
+                val_buf.len() / std::mem::size_of::<i128>(),
+                None,
+                None,
+                0,
+                vec![val_buf],
+                vec![],
+            )
+        };
+        DecimalArray::from(data)
+    }
+
+    /// Return the precision (total digits) that can be stored by this array
     pub fn precision(&self) -> usize {
         self.precision
     }
 
+    /// Return the scale (digits after the decimal) that can be stored by this array
     pub fn scale(&self) -> usize {
         self.scale
     }
+
+    /// Returns a DecimalArray with the same data as self, with the
+    /// specified precision.
+    ///
+    /// panic's if:
+    /// 1. the precision is larger than [`DECIMAL_MAX_PRECISION`]
+    /// 2. scale is larger than [`DECIMAL_MAX_SCALE`];
+    /// 3. scale is > precision
+    pub fn with_precision_and_scale(mut self, precision: usize, scale: usize) -> Self {

Review comment:
       I think `Result` is better.




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