ARROW-14817 [R] Implement bindings for lubridate::tz()

r/NEWS.md

@@ -19,6 +19,9 @@
 
 # arrow 7.0.0.9000
 
+* `lubridate`: 
+  * `tz()` to extract/get timezone
+
 # arrow 7.0.0
 
 ## Enhancements to dplyr and datasets

r/R/dplyr-funcs-datetime.R

@@ -147,5 +147,11 @@ register_bindings_datetime <- function() {
   register_binding("pm", function(x) {
     !call_binding("am", x)
   })
+  register_binding("tz", function(x) {
+    if (!call_binding("is.POSIXct", x)) {
+      abort(paste0("timezone extraction for objects of class `", type(x)$ToString(), "` not supported in Arrow"))
+    }
 
+    x$type()$timezone()
+  })
 }

r/R/type.R

@@ -78,7 +78,7 @@ type.default <- function(x) Array__infer_type(x)
 type.ArrowDatum <- function(x) x$type
 
 #' @export
-type.Expression <- function(x) x$type
+type.Expression <- function(x) x$type()
 
 #----- metadata
 

r/tests/testthat/test-dplyr-funcs-datetime.R

@@ -711,3 +711,41 @@ test_that("am/pm mirror lubridate", {
   )
 
 })
+
+test_that("extract tz", {
+  df <- tibble(
+    posixct_date = as.POSIXct(c("2022-02-07", "2022-02-10"), tz = "Pacific/Marquesas"),
+  )
+
+  compare_dplyr_binding(
+    .input %>%
+      mutate(timezone_posixct_date = tz(posixct_date)) %>%
+      collect(),
+    df
+  )
+
+  # test a few types directly from R objects
+  expect_error(
+    call_binding("tz", "2020-10-01"),
+    "timezone extraction for objects of class `string` not supported in Arrow"
+  )
+  expect_error(
+    call_binding("tz", as.Date("2020-10-01")),
+    "timezone extraction for objects of class `date32[day]` not supported in Arrow",
+    fixed = TRUE
+  )
+  expect_error(
+    call_binding("tz", 1L),
+    "timezone extraction for objects of class `int32` not supported in Arrow"
+  )
+   expect_error(
+    call_binding("tz", 1.1),
+    "timezone extraction for objects of class `double` not supported in Arrow"
+  )
+
+  # Test one expression
+  expect_error(
+    call_binding("tz", Expression$scalar("2020-10-01")),
+    "timezone extraction for objects of class `string` not supported in Arrow"
+  )
+})

r/tests/testthat/test-type.R

@@ -235,7 +235,10 @@ test_that("type() gets the right type for Expression", {
   y <- Expression$scalar(10)
   add_xy <- Expression$create("add", x, y)
 
-  expect_equal(x$type, type(x))
-  expect_equal(y$type, type(y))
-  expect_equal(add_xy$type, type(add_xy))
+  expect_equal(x$type(), type(x))
+  expect_equal(type(x), int32())
+  expect_equal(y$type(), type(y))
+  expect_equal(type(y), float64())
+  expect_equal(add_xy$type(), type(add_xy))
+  expect_equal(type(add_xy), float64())
 })