dragosmg commented on a change in pull request #12433:
URL: https://github.com/apache/arrow/pull/12433#discussion_r816672986
##########
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
Review comment:
Is `safe = FALSE` what you had in mind?
``` r
suppressPackageStartupMessages(library(arrow))
a <- Array$create(32.45)
a$cast(int32())
#> Error: Invalid: Float value 32.45 was truncated converting to int32
#>
/Users/dragos/Documents/arrow/cpp/src/arrow/compute/kernels/scalar_cast_numeric.cc:177
CheckFloatToIntTruncation(batch[0], *out)
#> /Users/dragos/Documents/arrow/cpp/src/arrow/compute/exec.cc:700
kernel_->exec(kernel_ctx_, batch, &out)
#> /Users/dragos/Documents/arrow/cpp/src/arrow/compute/exec.cc:641
ExecuteBatch(batch, listener)
#> /Users/dragos/Documents/arrow/cpp/src/arrow/compute/function.cc:255
executor->Execute(implicitly_cast_args, &listener)
a$cast(int32(), safe = FALSE)
#> Array
#> <int32>
#> [
#> 32
#> ]
```
<sup>Created on 2022-03-01 by the [reprex
package](https://reprex.tidyverse.org) (v2.0.1)</sup>
Ideally we would support float -> date casting
([ARROW-15807](https://issues.apache.org/jira/browse/ARROW-15807)
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