Oh, to reverse by index ... I think this doesn't quite fit in the idea of sorts defined by an ordering function purely dependent on the value of the element.
I think there may have been a feature request <https://github.com/golang/go/issues/47988> for a `slices.Reverse` function in golang.org/x/exp/slices - I'm not sure what the status or reasoning is on this. FWIW it's not the only approach that might make sense for traversing a slice in reverse order, and it can be naive when working with e.g. bytes holding utf8. I think this works but I haven't really thought about edge cases... `reverse(&s)` func reverse[T any](s *[]T) { z := len(*s) for a := 0; a < len(*s)/2; a++ { (*s)[a], (*s)[z-a-1] = (*s)[z-a-1], (*s)[a] } } On Tuesday, December 6, 2022 at 6:54:38 PM UTC-8 hey...@gmail.com wrote: > Thanks for the quick reply. > > But that seems to compare values. I'd like to compare index numbers. The > fact that original values follow index number order is a coincidence. > > > I think it'd be recommended to look at the generics slices package, > which also has a sort > > Do you mean golang.org/x/exp/slices? That also seems to only compare > values. > > > On Wednesday, December 7, 2022 at 10:45:33 AM UTC+8 harr...@spu.edu wrote: > >> Subtly: >> return s[i] > s[j] >> >> Is the right sort func >> >> I think it'd be recommended to look at the generics slices package, which >> also has a sort >> On Tuesday, December 6, 2022 at 6:39:29 PM UTC-8 hey...@gmail.com wrote: >> >>> Hi, >>> >>> I have this very simple sorting code: >>> >>> s := make([]int, 0, 100) >>> for i := 1; i <= 20; i++ { >>> s = append(s, i) >>> } >>> sort.Slice(s, func(i, j int) bool { return i > j }) >>> log.Print(s) >>> >>> I expect it to print numbers in reverse order, since items with larger >>> index numbers should be at the front. However, at lease in go1.19.3, it >>> prints >>> >>> [9 1 8 5 16 3 20 2 10 7 12 13 14 15 6 4 19 18 17 11] >>> >>> I guess I must have misunderstood how the sort package works, but >>> rereading sort's doc multiple time doesn't help answer the question. >>> >>> Could anyone shed some light? >>> >> -- You received this message because you are subscribed to the Google Groups "golang-nuts" group. To unsubscribe from this group and stop receiving emails from it, send an email to golang-nuts+unsubscr...@googlegroups.com. To view this discussion on the web visit https://groups.google.com/d/msgid/golang-nuts/859114fe-6d0a-4747-9f6d-298392070eefn%40googlegroups.com.
