nealrichardson commented on a change in pull request #10507:
URL: https://github.com/apache/arrow/pull/10507#discussion_r657236041
##########
File path: r/R/dplyr-functions.R
##########
@@ -442,3 +442,30 @@ nse_funcs$strptime <- function(x, format = "%Y-%m-%d
%H:%M:%S", tz = NULL, unit
Expression$create("strptime", x, options = list(format = format, unit =
unit))
}
+
+nse_funcs$second <- function(x) {
+ Expression$create("add", Expression$create("second", x),
Expression$create("subsecond", x))
+}
+
+# After ARROW-13054 is completed, we can refactor this for simplicity
+#
+# Arrow's `day_of_week` kernel counts from 0 (Monday) to 6 (Sunday), whereas
+# `lubridate::wday` counts from 1 to 7, and allows users to specify which day
+# of the week is first (Sunday by default). This Expression converts the
returned
+# day of the week back to the value that would be returned by lubridate by
+# providing offset values based on the specified week_start day, and adding 1
+# so the returned value is 1-indexed instead of 0-indexed.
+nse_funcs$wday <- function(x, label = FALSE, abbr = TRUE, week_start =
getOption("lubridate.week.start", 7)) {
+
+ # The "day_of_week" compute function returns numeric days of week and not
locale-aware strftime
+ # When the ticket below is resolved, we should be able to support the label
argument
+ # https://issues.apache.org/jira/browse/ARROW-13133
+ if (label) {
+ arrow_not_supported("Label argument")
+ }
+
+ # overall formula to convert from arrow::wday to lubridate::wday is:
+ # ((wday(day) - start + 8) %% 7) + 1
+ ((Expression$create("day_of_week", x) - Expression$scalar(week_start) + 8)
%% 7) + 1
Review comment:
```suggestion
((Expression$create("day_of_week", x) - Expression$scalar(week_start) + 8)
%% 7) + 1
```
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