paleolimbot commented on code in PR #12817:
URL: https://github.com/apache/arrow/pull/12817#discussion_r852234012
##########
r/R/record-batch-reader.R:
##########
@@ -176,3 +176,37 @@ RecordBatchFileReader$create <- function(file) {
assert_is(file, "InputStream")
ipc___RecordBatchFileReader__Open(file)
}
+
+#' Convert an object to an Arrow RecordBatchReader
+#'
+#' @param x An object to convert to a [RecordBatchReader]
+#' @param ... Passed to S3 methods
+#'
+#' @return A [RecordBatchReader]
+#' @export
+#'
+#' @examplesIf arrow_available() && arrow_with_dataset()
+#' reader <- as_record_batch_reader(data.frame(col1 = 1, col2 = "two"))
+#' reader$read_next_batch()
+#'
+as_record_batch_reader <- function(x, ...) {
+ UseMethod("as_record_batch_reader")
+}
+
+#' @rdname as_record_batch_reader
+#' @export
+as_record_batch_reader.RecordBatchReader <- function(x, ...) {
+ x
+}
+
+#' @rdname as_arrow_table
+#' @export
+as_record_batch_reader.default <- function(x, ...) {
+ Scanner$create(x)$ToRecordBatchReader()
Review Comment:
That's a good point and it definitely shouldn't be in the default method. Is
there a better bit of code I should use to handle all the ArrowTabulars
(data.frame, Dataset, Table, RecordBatch, etc?). I don't think we have to
provide any guarantees about the result or keep the options stable across
versions (if a user or developer does want to provide options regarding size or
ordering of batches, they can create a `RecordBatchReader` themselves?).
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