ianmcook commented on a change in pull request #9586:
URL: https://github.com/apache/arrow/pull/9586#discussion_r588576224
##########
File path: r/R/dataset-scan.R
##########
@@ -157,13 +157,19 @@ ScannerBuilder <- R6Class("ScannerBuilder", inherit =
ArrowObject,
public = list(
Project = function(cols) {
# cols is either a character vector or a named list of Expressions
- if (!is.character(cols)) {
- # We don't yet support mutate() on datasets, so this is just a list
- # of FieldRefs, and we need to back out the field names
- cols <- get_field_names(cols)
+ if (is.character(cols)) {
+ dataset___ScannerBuilder__ProjectNames(self, cols)
Review comment:
In what circumstance will `is.character(cols)` be `TRUE`? I've running a
bunch of examples and I've never seen the code take this path.
##########
File path: r/R/dataset-scan.R
##########
@@ -157,13 +157,19 @@ ScannerBuilder <- R6Class("ScannerBuilder", inherit =
ArrowObject,
public = list(
Project = function(cols) {
# cols is either a character vector or a named list of Expressions
- if (!is.character(cols)) {
- # We don't yet support mutate() on datasets, so this is just a list
- # of FieldRefs, and we need to back out the field names
- cols <- get_field_names(cols)
+ if (is.character(cols)) {
+ dataset___ScannerBuilder__ProjectNames(self, cols)
Review comment:
In what circumstance will `is.character(cols)` be `TRUE`? I've been
running a bunch of examples and I've never seen the code take this path.
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