[GitHub] [arrow-rs] alamb commented on a diff in pull request #2052: feat(compute): Support DOW (day of week) for temporal

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

alamb commented on code in PR #2052:
URL: https://github.com/apache/arrow-rs/pull/2052#discussion_r919189389


##########
arrow/src/compute/kernels/temporal.rs:
##########
@@ -112,32 +112,62 @@ macro_rules! return_compute_error_with {
     };
 }
 
-trait ChronoDateQuarter {
+// Internal trait, which is used for mapping values from DateLike structures
+trait ChronoDateExt {
     /// Returns a value in range `1..=4` indicating the quarter this date falls into
     fn quarter(&self) -> u32;
 
     /// Returns a value in range `0..=3` indicating the quarter (zero-based) this date falls into
     fn quarter0(&self) -> u32;
+
+    fn weekday_from_sunday(&self) -> i32;
 }
 
-impl ChronoDateQuarter for NaiveDateTime {
+impl<T: Datelike> ChronoDateExt for T {
     fn quarter(&self) -> u32 {
         self.quarter0() + 1
     }
 
     fn quarter0(&self) -> u32 {
         self.month0() / 3
     }
-}
 
-impl ChronoDateQuarter for NaiveDate {
-    fn quarter(&self) -> u32 {
-        self.quarter0() + 1
+    fn weekday_from_sunday(&self) -> i32 {
+        self.weekday().num_days_from_sunday() as i32
     }
+}
 
-    fn quarter0(&self) -> u32 {
-        self.month0() / 3
+/// Extracts the day of week of a given temporal array as an array of integers
+pub fn dow<T>(array: &PrimitiveArray<T>) -> Result<Int32Array>

Review Comment:
   I wonder how this is different than `weekday`: https://docs.rs/arrow/18.0.0/arrow/compute/kernels/temporal/fn.weekday.html (defined on line 304 of this same file)?



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