jonkeane commented on a change in pull request #10724:
URL: https://github.com/apache/arrow/pull/10724#discussion_r671334301
##########
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:
_turns out_ we're not quite there yet — the last (common) type that's
not yet implemented still is factors/dictionaries. Currently they are auto
decoded into strings — which is better than nothing, but not quite right.
I can use the (fragile) `is.factor()` approach here to warn that though we
are getting factors, we are returning strings (for now) or we could silently do
the conversation with no checking. Or, I guess we could also disable factors
entirely, but that seems extreme. I vote that we warn so that there's no
confusion about the change in type, even if it is a bit fragile.
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