[GitHub] [arrow] ianmcook commented on a change in pull request #10261: ARROW-11769: [R] Pull groups from grouped_df into RecordBatch or Table

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

ianmcook commented on a change in pull request #10261:
URL: https://github.com/apache/arrow/pull/10261#discussion_r627893108



##########
File path: r/R/record-batch.R
##########
@@ -148,13 +148,20 @@ RecordBatch$create <- function(..., schema = NULL) {
   if (length(arrays) == 1 && inherits(arrays[[1]], c("raw", "Buffer", "InputStream", "Message"))) {
     return(RecordBatch$from_message(arrays[[1]], schema))
   }
+  
   # Else, list of arrays
   # making sure there are always names
   if (is.null(names(arrays))) {
     names(arrays) <- rep_len("", length(arrays))
   }
   stopifnot(length(arrays) > 0)
 
+  # Preserve any grouping
+  if (length(arrays) == 1 && inherits(arrays[[1]], "grouped_df")) {
+    out <- RecordBatch__from_arrays(schema, arrays)
+    return(group_by(out, !!!groups(arrays[[1]])))

Review comment:
       dplyr is not in Arrow's Depends or Imports, so we need to use `dplyr::` before `group_by` and other dplyr functions. This line will error if dplyr is not installed, but that's reasonable because it's enclosed in a conditional that should prevent it from being run in most cases where dplyr is not installed 
   ```suggestion
       return(dplyr::group_by(out, !!!groups(arrays[[1]])))
   ```




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