dragosmg commented on code in PR #12738:
URL: https://github.com/apache/arrow/pull/12738#discussion_r854382238
##########
r/R/dplyr-funcs-datetime.R:
##########
@@ -372,3 +372,50 @@ binding_format_datetime <- function(x, format = "", tz =
"", usetz = FALSE) {
build_expr("strftime", x, options = list(format = format, locale =
Sys.getlocale("LC_TIME")))
}
+
+binding_as_date <- function(x,
+ format = NULL,
+ tryFormats = "%Y-%m-%d",
+ origin = "1970-01-01",
+ tz = "UTC",
+ base = TRUE) {
+
+ if (is.null(format) && length(tryFormats) > 1) {
+ abort("`as.Date()` with multiple `tryFormats` is not supported in Arrow")
+ }
+
+ if (call_binding("is.Date", x)) {
+ return(x)
+
+ # cast from POSIXct
+ } else if (call_binding("is.POSIXct", x)) {
+ # base::as.Date() first converts to the desired timezone and then extracts
+ # the date, which is why we need to go through timestamp() first
+ if (base || !is.null(tz)) {
+ x <- build_expr("cast", x, options = cast_options(to_type =
timestamp(timezone = tz)))
+ }
+ # POSIXct is of type double -> we need this to prevent going down the
+ # "double" branch
+ x <- x
+
+ # cast from character
+ } else if (call_binding("is.character", x)) {
+ format <- format %||% tryFormats[[1]]
+ # unit = 0L is the identifier for seconds in valid_time32_units
+ x <- build_expr("strptime", x, options = list(format = format, unit = 0L))
+
+ # cast from numeric
+ } else if (call_binding("is.numeric", x) &
+ (!call_binding("is.integer", x) | origin != "1970-01-01")) {
+ # Arrow does not support direct casting from double to date32(), but for
+ # integer-like values we can go via int32()
+ # https://issues.apache.org/jira/browse/ARROW-15798
+ # TODO revisit if arrow decides to support double -> date casting
+ x <- build_expr("cast", x, options = cast_options(to_type = int32()))
+ delta_in_sec <- call_binding("difftime", origin, "1970-01-01")
+ delta_in_sec <- build_expr("cast", delta_in_sec, options =
cast_options(to_type = int64()))
+ delta_in_days <- (delta_in_sec / 86400L)$cast(int32())
+ x <- build_expr("+", x, delta_in_days)
Review Comment:
On the Jira for the cast from `duration` to `int32`. There isn't one. I'm
not sure how clearly documented this is, but it seems int64 is the matching
type for quite a bit of the date-time/ duration types. We could extend the
scope of [ARROW-15858](https://issues.apache.org/jira/browse/ARROW-15858)?
Would that make sense?
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