liukun4515 commented on a change in pull request #1223:
URL: https://github.com/apache/arrow-rs/pull/1223#discussion_r790371475
##########
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 {
+ assert!(
+ precision <= DECIMAL_MAX_PRECISION,
+ "precision {} is greater than max {}",
+ precision,
+ DECIMAL_MAX_PRECISION
+ );
+ assert!(
+ scale <= DECIMAL_MAX_SCALE,
+ "scale {} is greater than max {}",
+ scale,
+ DECIMAL_MAX_SCALE
+ );
+ assert!(
+ scale <= precision,
+ "scale {} is greater than precision {}",
+ scale,
+ precision
+ );
+
+ assert_eq!(
+ self.data.data_type(),
+ &DataType::Decimal(self.precision, self.scale)
+ );
+
+ // safety: self.data is valid DataType::Decimal
+ let new_data_type = DataType::Decimal(precision, scale);
+ self.precision = precision;
+ self.scale = scale;
+ self.data = self.data.with_data_type(new_data_type);
+ self
+ }
+
+ /// The default precision and scale used when not specified
+ pub fn default_type() -> DataType {
+ // Keep maximum precision
+ DataType::Decimal(38, 10)
Review comment:
we can replace 38 to `DECIMAL_MAX_PRECISION`, and 10 to
`OTHER_DEFAULT_VALUE`.
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