[GitHub] [arrow] dragosmg commented on a change in pull request #12433: ARROW-14808 [R] Implement bindings for `lubridate::date()`

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

dragosmg commented on a change in pull request #12433:
URL: https://github.com/apache/arrow/pull/12433#discussion_r816583722



##########
File path: r/R/dplyr-funcs-type.R
##########
@@ -76,6 +76,64 @@ register_bindings_type_cast <- function() {
   register_binding("as.numeric", function(x) {
     Expression$create("cast", x, options = cast_options(to_type = float64()))
   })
+  register_binding("as.Date", function(x,
+                                       format = NULL,
+                                       tryFormats = "%Y-%m-%d",
+                                       origin = "1970-01-01",
+                                       tz = "UTC") {
+
+    if (call_binding("is.Date", 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
+      return(x)
+
+    # cast from POSIXct
+    } else if (call_binding("is.POSIXct", x)) {
+      if (tz == "UTC") {
+        interim_x <- build_expr("cast", x, options = cast_options(to_type = timestamp(timezone = tz)))
+      } else {
+        abort("`as.Date()` with a timezone different to 'UTC' is not supported in Arrow")
+      }
+
+    # cast from character
+    } else if (call_binding("is.character", x)) {
+      # this could be improved with tryFormats once strptime returns NA and we
+      # can use coalesce - https://issues.apache.org/jira/browse/ARROW-15659
+      # TODO revisit once https://issues.apache.org/jira/browse/ARROW-15659 is done
+      if (is.null(format)) {
+        if (length(tryFormats) == 1) {
+          format <- tryFormats[1]
+        } else {
+          abort("`as.Date()` with multiple `tryFormats` is not supported in Arrow yet")
+        }
+      }
+      # if x is not an expression (e.g. passed as filter), convert it to one
+      if (!inherits(x, "Expression")) {
+        x <- build_expr("cast", x, options = cast_options(to_type = type(x)))
+      }
+      interim_x <- call_binding("strptime", x, format, unit = "s")
+
+    # cast from numeric
+    } else if (call_binding("is.numeric", x)) {
+      # the origin argument will be better supported once we implement temporal
+      # arithmetic (https://issues.apache.org/jira/browse/ARROW-14947)
+      # TODO revisit once the above has been sorted
+      if (!call_binding("is.integer", x)) {
+        # Arrow does not support direct casting from double to date so we have
+        # to convert to integers first - casting to int32() would error so we
+        # need to use round before casting
+        # TODO revisit if arrow decides to support double -> date casting
+        x <- call_binding("floor", x)
+        interim_x <- build_expr("cast", x, options = (cast_options(to_type = int32())))
+      } else {
+        interim_x <- x
+      }

Review comment:
       Done. 




-- 
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.

To unsubscribe, e-mail: github-unsubscribe@arrow.apache.org

For queries about this service, please contact Infrastructure at:
users@infra.apache.org