ARROW-3439: [R] R language bindings for Feather format

r/DESCRIPTION

@@ -55,6 +55,7 @@ Collate:
     'array.R'
     'buffer.R'
     'dictionary.R'
+    'feather.R'
     'io.R'
     'memory_pool.R'
     'message.R'

r/NAMESPACE

@@ -14,6 +14,12 @@ S3method(buffer,numeric)
 S3method(buffer,raw)
 S3method(buffer_reader,"arrow::Buffer")
 S3method(buffer_reader,default)
+S3method(feather_table_reader,"arrow::io::RandomAccessFile")
+S3method(feather_table_reader,"arrow::ipc::feather::TableReader")
+S3method(feather_table_reader,character)
+S3method(feather_table_reader,default)
+S3method(feather_table_reader,fs_path)
+S3method(feather_table_writer,"arrow::io::OutputStream")
 S3method(fixed_size_buffer_writer,"arrow::Buffer")
 S3method(fixed_size_buffer_writer,default)
 S3method(length,"arrow::Array")
@@ -51,6 +57,13 @@ S3method(record_batch_stream_reader,raw)
 S3method(write_arrow,"arrow::RecordBatch")
 S3method(write_arrow,"arrow::Table")
 S3method(write_arrow,data.frame)
+S3method(write_feather,"arrow::RecordBatch")
+S3method(write_feather,data.frame)
+S3method(write_feather,default)
+S3method(write_feather_RecordBatch,"arrow::io::OutputStream")
+S3method(write_feather_RecordBatch,character)
+S3method(write_feather_RecordBatch,default)
+S3method(write_feather_RecordBatch,fs_path)
 S3method(write_record_batch,"arrow::io::OutputStream")
 S3method(write_record_batch,"arrow::ipc::RecordBatchWriter")
 S3method(write_record_batch,character)
@@ -78,6 +91,8 @@ export(date32)
 export(date64)
 export(decimal)
 export(dictionary)
+export(feather_table_reader)
+export(feather_table_writer)
 export(file_open)
 export(file_output_stream)
 export(fixed_size_buffer_writer)
@@ -96,6 +111,7 @@ export(mock_output_stream)
 export(null)
 export(print.integer64)
 export(read_arrow)
+export(read_feather)
 export(read_message)
 export(read_record_batch)
 export(read_schema)
@@ -118,6 +134,8 @@ export(uint64)
 export(uint8)
 export(utf8)
 export(write_arrow)
+export(write_feather)
+export(write_feather_RecordBatch)
 export(write_record_batch)
 export(write_table)
 importFrom(R6,R6Class)

r/R/feather.R

@@ -0,0 +1,160 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+#' @include R6.R
+
+`arrow::ipc::feather::TableWriter` <- R6Class("arrow::ipc::feather::TableWriter", inherit = `arrow::Object`,
+  public = list(
+    SetDescription = function(description) ipc___feather___TableWriter__SetDescription(self, description),
+    SetNumRows = function(num_rows) ipc___feather___TableWriter__SetNumRows(self, num_rows),
+    Append = function(name, values) ipc___feather___TableWriter__Append(self, name, values),
+    Finalize = function() ipc___feather___TableWriter__Finalize(self)
+  )
+)
+
+`arrow::ipc::feather::TableReader` <- R6Class("arrow::ipc::feather::TableReader", inherit = `arrow::Object`,
+  public = list(
+    GetDescription = function() ipc___feather___TableReader__GetDescription(self),
+    HasDescription = function() ipc__feather___TableReader__HasDescription(self),
+    version = function() ipc___feather___TableReader__version(self),
+    num_rows = function() ipc___feather___TableReader__num_rows(self),
+    num_columns = function() ipc___feather___TableReader__num_columns(self),
+    GetColumnName = function(i) ipc___feather___TableReader__GetColumnName(self, i),
+    GetColumn = function(i) shared_ptr(`arrow::Column`, ipc___feather___TableReader__GetColumn(self, i)),
+    Read = function() shared_ptr(`arrow::Table`, ipc___feather___TableReader__Read(self))
+  )
+)
+
+#' Create TableWriter that writes into a stream
+#'
+#' @param stream an OutputStream
+#'
+#' @export
+feather_table_writer <- function(stream) {
+  UseMethod("feather_table_writer")
+}
+
+#' @export
+`feather_table_writer.arrow::io::OutputStream` <- function(stream){
+  unique_ptr(`arrow::ipc::feather::TableWriter`, ipc___feather___TableWriter__Open(stream))
+}
+
+#' Write data in the feather format
+#'
+#' @param data frame or arrow::RecordBatch
+#' @param stream A file path or an arrow::io::OutputStream
+#'
+#' @export
+write_feather <- function(data, stream) {
+  UseMethod("write_feather", data)
+}
+
+#' @export
+write_feather.default <- function(data, stream) {
+  stop("unsupported")
+}
+
+#' @export
+write_feather.data.frame <- function(data, stream) {
+  write_feather(record_batch(data), stream)
+}
+
+#' @method write_feather arrow::RecordBatch
+#' @export
+`write_feather.arrow::RecordBatch` <- function(data, stream) {
+  write_feather_RecordBatch(data, stream)
+}
+
+#' @rdname write_feather
+#' @export
+write_feather_RecordBatch <- function(data, stream) {
+  UseMethod("write_feather_RecordBatch", stream)
+}
+
+#' @export
+#' @method write_feather_RecordBatch default
+`write_feather_RecordBatch.default` <- function(data, stream) {
+  stop("unsupported")
+}
+
+#' @export
+#' @method write_feather_RecordBatch character
+`write_feather_RecordBatch.character` <- function(data, stream) {
+  `write_feather_RecordBatch.fs_path`(data, fs::path_abs(stream))
+}
+
+#' @export
+#' @method write_feather_RecordBatch fs_path
+`write_feather_RecordBatch.fs_path` <- function(data, stream) {
+  file_stream <- close_on_exit(file_output_stream(stream))
+  `write_feather_RecordBatch.arrow::io::OutputStream`(data, file_stream)
+}
+
+#' @export
+#' @method write_feather_RecordBatch arrow::io::OutputStream
+`write_feather_RecordBatch.arrow::io::OutputStream` <- function(data, stream) {
+  ipc___TableWriter__RecordBatch__WriteFeather(feather_table_writer(stream), data)
+}
+
+#' A arrow::ipc::feather::TableReader to read from a file
+#'
+#' @param file A file path, arrow::io::RandomAccessFile
+#' @param mmap Is the file memory mapped (applicable to the character and fs_path methods)
+#' @param ... extra parameters
+#'
+#' @export
+feather_table_reader <- function(file, mmap = TRUE, ...){
+  UseMethod("feather_table_reader")
+}
+
+#' @export
+feather_table_reader.default <- function(file, mmap = TRUE, ...) {
+  stop("unsupported")
+}
+
+#' @export
+feather_table_reader.character <- function(file, mmap = TRUE, ...) {
+  feather_table_reader(fs::path_abs(file), mmap = mmap, ...)
+}
+
+#' @export
+feather_table_reader.fs_path <- function(file, mmap = TRUE, ...) {
+  stream <- if(isTRUE(mmap)) mmap_open(file, ...) else file_open(file, ...)
+  feather_table_reader(stream)
+}
+
+#' @export
+`feather_table_reader.arrow::io::RandomAccessFile` <- function(file, mmap = TRUE, ...){
+  unique_ptr(`arrow::ipc::feather::TableReader`, ipc___feather___TableReader__Open(file))
+}
+
+#' @export
+`feather_table_reader.arrow::ipc::feather::TableReader` <- function(file, mmap = TRUE, ...){
+  file
+}
+
+#' Read a feather file
+#'
+#' @param file a arrow::ipc::feather::TableReader or whatever the [feather_table_reader()] function can handle
+#' @param ... additional parameters
+#'
+#' @return an arrow::Table
+#'
+#' @export
+read_feather <- function(file, ...){
+  feather_table_reader(file, ...)$Read()
+}