[GitHub] [arrow] jonkeane commented on a change in pull request #10724: ARROW-12964: [R] Add bindings for ifelse() and if_else()

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

jonkeane commented on a change in pull request #10724:
URL: https://github.com/apache/arrow/pull/10724#discussion_r682676388



##########
File path: r/R/dplyr-functions.R
##########
@@ -634,20 +634,53 @@ nse_funcs$wday <- function(x, label = FALSE, abbr = TRUE, week_start = getOption
 }
 
 nse_funcs$log <- function(x, base = exp(1)) {
-  
+
   if (base == exp(1)) {
     return(Expression$create("ln_checked", x))
   }
-  
+
   if (base == 2) {
     return(Expression$create("log2_checked", x))
   }
-  
+
   if (base == 10) {
     return(Expression$create("log10_checked", x))
-  } 
+  }
   # ARROW-13345
   stop("`base` values other than exp(1), 2 and 10 not supported in Arrow", call. = FALSE)
 }
 
 nse_funcs$logb <- nse_funcs$log
+
+nse_funcs$if_else <- function(condition, true, false, missing = NULL){
+  # We ought to assert that the types of the true and false conditions will result
+  # in the same types. We can't compare the objects themselves directly because
+  # they might be expressions (that will result in a type) or R objects that will
+  # need to be compared to see if they are compatible with arrow types.
+  # ARROW-13186 might make this easier with a more robust way.
+  # TODO: do this ^^^
+
+  # if_else only supports boolean, numeric, or temporal types right now
+  # TODO: remove when ARROW-12955 merges
+  # If true/false are R types, we can use `is.*` directly
+  invalid_r_types <- is.character(true) || is.character(false) || is.list(true) ||
+    is.list(false) || is.factor(true) || is.factor(false)
+  # However, if they are expressions, we need to use the functions from nse_funcs
+  invalid_expression_types_true <- inherits(true, "Expression") && (
+    nse_funcs$is.character(true) || nse_funcs$is.list(true) || nse_funcs$is.factor(true)
+  )
+  invalid_expression_types_false <- inherits(false, "Expression") && (
+    nse_funcs$is.character(false) || nse_funcs$is.list(false) || nse_funcs$is.factor(false)
+  )
+  if (invalid_r_types | invalid_expression_types_true | invalid_expression_types_false) {
+    stop("`true` and `false` character values not yet supported in Arrow", call. = FALSE)
+  }

Review comment:
       I would say that the base R version here is wrong / never what someone actually wants.
   
   I don't think we want to get into the business of coalescing/merging the dictionaries to be the same (there are many edge cases that can lead to very funny outcomes). But emulating the dplyr behavior seems reasonable here (use the levels of the first, merge the values together and any value that's not in the levels of the first gets an NA + warning that the dictionaries didn't match)




-- 
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