stuartcarnie commented on code in PR #2251:
URL: https://github.com/apache/arrow-rs/pull/2251#discussion_r934943090
##########
arrow/src/compute/kernels/cast.rs:
##########
@@ -1584,6 +1625,303 @@ fn cast_string_to_date64<Offset: OffsetSizeTrait>(
Ok(Arc::new(array) as ArrayRef)
}
+fn seconds_since_midnight(time: &chrono::NaiveTime) -> i32 {
+ let sec = time.num_seconds_from_midnight();
+ let frac = time.nanosecond();
+ let adjust = if frac < 1_000_000_000 { 0 } else { 1 };
+ (sec + adjust) as i32
+}
+
+fn milliseconds_since_midnight(time: &chrono::NaiveTime) -> i32 {
+ /// The number of nanoseconds per millisecond.
+ const NANOS_PER_MILLI: u32 = 1_000_000;
+ /// The number of milliseconds per second.
+ const MILLIS_PER_SEC: u32 = 1_000;
+
+ let sec = time.num_seconds_from_midnight() * MILLIS_PER_SEC;
+ let frac = time.nanosecond();
+ let (frac, adjust) = if frac < 1_000_000_000 {
+ (frac, 0)
+ } else {
+ (frac - 1_000_000_000, MILLIS_PER_SEC)
+ };
+ (sec + adjust + frac / NANOS_PER_MILLI) as i32
+}
+
+/// Casts generic string arrays to `Time32SecondArray`
+fn cast_string_to_time32second<Offset: OffsetSizeTrait>(
+ array: &dyn Array,
+ cast_options: &CastOptions,
+) -> Result<ArrayRef> {
+ let string_array = array
+ .as_any()
+ .downcast_ref::<GenericStringArray<Offset>>()
+ .unwrap();
+
+ let array = if cast_options.safe {
+ let iter = (0..string_array.len()).map(|i| {
+ if string_array.is_null(i) {
+ None
+ } else {
+ string_array
+ .value(i)
+ .parse::<chrono::NaiveTime>()
+ .map(|time| seconds_since_midnight(&time))
+ .ok()
+ }
+ });
Review Comment:
Sounds good – it looks like the string to date transformation functions
would benefit from the same treatment, but I'll leave that to another PR so as
to not cloud this one.
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