[GitHub] [arrow] thisisnic commented on a change in pull request #10141: ARROW-11787: [R] Implement write csv

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

thisisnic commented on a change in pull request #10141:
URL: https://github.com/apache/arrow/pull/10141#discussion_r624049352



##########
File path: r/R/csv.R
##########
@@ -585,3 +613,55 @@ readr_to_csv_convert_options <- function(na,
     include_columns = include_columns
   )
 }
+
+#' Write CSV file to disk
+#'
+#' @param x `data.frame`, [RecordBatch], or [Table]
+#' @param sink A string file path, URI, or [OutputStream], or path in a file
+#' system (`SubTreeFileSystem`)
+#' @param include_header Whether to write an initial header line with column names
+#' @param batch_size Maximum number of rows processed at a time. Default is 1024.
+#'
+#' @return The input `x`, invisibly. Note that if `sink` is an [OutputStream],
+#' the stream will be left open.
+#' @export
+#' @examples
+#' \donttest{
+#' tf <- tempfile()
+#' on.exit(unlink(tf))
+#' write_csv_arrow(mtcars, tf)
+#' }
+#' @include arrow-package.R
+write_csv_arrow <- function(x,
+                          sink,
+                          include_header = TRUE,
+                          batch_size = 1024L
+                          ) {
+  # Handle and validate options before touching data
+  batch_size <- as.integer(batch_size)
+  assert_that(batch_size > 0)

Review comment:
       I get the below error.  Shall I remove the assertion as it'd handled at the C++ level, or leave it in as it's a cleaner error message with `assert_that`?
   
   ```
   Error: Invalid: Negative buffer resize: -40
   /home/nic2/arrow/cpp/src/arrow/buffer.cc:262  buffer->Resize(size)
   /home/nic2/arrow/cpp/src/arrow/csv/writer.cc:337  AllocateResizableBuffer( options.batch_size * schema_->num_fields() * kColumnSizeGuess, pool_)
   /home/nic2/arrow/cpp/src/arrow/csv/writer.cc:315  PrepareForContentsWrite(options, out)
   ```




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