ARROW-12841: [R] Add examples to more function documentation - part 2

r/DESCRIPTION

@@ -36,7 +36,7 @@ Imports:
     utils,
     vctrs
 Roxygen: list(markdown = TRUE, r6 = FALSE, load = "source")
-RoxygenNote: 7.1.1
+RoxygenNote: 7.1.1.9001
 VignetteBuilder: knitr
 Suggests:
     decor,

r/R/compression.R

@@ -63,6 +63,8 @@ Codec$create <- function(type = "gzip", compression_level = NA) {
 #' "zstd", "lz4", "lzo", or "bz2", case insensitive.
 #' @return Logical: is `type` available?
 #' @export
+#' @examples
+#' codec_is_available("gzip")
 codec_is_available <- function(type) {
   util___Codec__IsAvailable(compression_from_name(type))
 }

r/R/dataset-format.R

@@ -53,6 +53,18 @@
 #' It returns the appropriate subclass of `FileFormat` (e.g. `ParquetFileFormat`)
 #' @rdname FileFormat
 #' @name FileFormat
+#' @examplesIf arrow_with_dataset()
+#' ## Semi-colon delimited files
+#' # Set up directory for examples
+#' tf <- tempfile()
+#' dir.create(tf)
+#' on.exit(unlink(tf))
+#' write.table(mtcars, file.path(tf, "file1.txt"), sep = ";", row.names = FALSE)
+#' 
+#' # Create FileFormat object
+#' format <- FileFormat$create(format = "text", delimiter = ";")
+#' 
+#' open_dataset(tf, format = format)
 #' @export
 FileFormat <- R6Class("FileFormat", inherit = ArrowObject,
   active = list(

r/R/dataset.R

@@ -69,6 +69,30 @@
 #' @export
 #' @seealso `vignette("dataset", package = "arrow")`
 #' @include arrow-package.R
+#' @examplesIf arrow_with_dataset()
+#' # Set up directory for examples
+#' tf <- tempfile()
+#' dir.create(tf)
+#' on.exit(unlink(tf))
+#' \dontrun{
+#' write_parquet(mtcars[1:10,], file.path(tf, "file1.parquet"))
+#' write_parquet(mtcars[11:20,], file.path(tf, "file2.parquet"))
+#' write_parquet(mtcars[21:32,], file.path(tf, "file3.parquet"))
+#' 
+#' # You can specify a directory containing the files for your dataset and
+#' # open_dataset will scan all files in your directory.
+#' open_dataset(tf)
+#' 
+#' # You can also supply a vector of paths
+#' open_dataset(c(file.path(tf, "file3.parquet"), file.path(tf, "file2.parquet")))
+#' }
+#' ## You must specify the file format if using a format other than parquet.
+#' write_csv_arrow(mtcars[1:10,], file.path(tf, "file1.csv"))
+#' write_csv_arrow(mtcars[11:20,], file.path(tf, "file2.csv"))
+#' # This line will results in errors when you try to work with the data
+#' \dontrun{open_dataset(c(file.path(tf, "file1.csv"), file.path(tf, "file2.csv")))}
+#' # This is the correct way to open a dataset containing CSVs
+#' open_dataset(c(file.path(tf, "file1.csv"), file.path(tf, "file2.csv")), format = "csv") 
 open_dataset <- function(sources,
                          schema = NULL,
                          partitioning = hive_partition(),

r/R/flight.R

@@ -21,6 +21,8 @@
 #' @param path file system path where the Python module is found. Default is
 #' to look in the `inst/` directory for included modules.
 #' @export
+#' @examples
+#' \dontrun{load_flight_server("demo_flight_server")}
 load_flight_server <- function(name, path = system.file(package = "arrow")) {
   reticulate::import_from_path(name, path)
 }

r/R/ipc_stream.R

@@ -35,6 +35,10 @@
 #' serialize data to a buffer.
 #' [RecordBatchWriter] for a lower-level interface.
 #' @export
+#' @examples 
+#' tf <- tempfile()
+#' on.exit(unlink(tf))
+#' write_ipc_stream(mtcars, tf)
 write_ipc_stream <- function(x, sink, ...) {
   x_out <- x # So we can return the data we got
   if (is.data.frame(x)) {

r/R/scalar.R

@@ -23,9 +23,33 @@
 #' @docType class
 #'
 #' @description A `Scalar` holds a single value of an Arrow type.
+#' 
+#' @section Methods:
+#'   `$ToString()`: convert to a string
+#'   `$as_vector()`: convert to an R vector
+#'   `$as_array()`: convert to an Arrow `Array`
+#'   `$Equals(other)`: is this Scalar equal to `other`
+#'   `$ApproxEquals(other)`: is this Scalar approximately equal to `other`
+#'   `$is_valid`: is this Scalar valid
+#'   `$null_count`: number of invalid values - 1 or 0 
+#'   `$type`: Scalar type
 #'
 #' @name Scalar
 #' @rdname Scalar
+#' @examples 
+#' Scalar$create(pi)
+#' Scalar$create(404)
+#' # If you pass a vector into Scalar$create, you get a list containing your items
+#' Scalar$create(c(1, 2, 3))
+#' 
+#' # Comparisons
+#' my_scalar <- Scalar$create(99)
+#' my_scalar$ApproxEquals(Scalar$create(99.00001)) # FALSE
+#' my_scalar$ApproxEquals(Scalar$create(99.000009)) # TRUE
+#' my_scalar$Equals(Scalar$create(99.000009)) # FALSE
+#' my_scalar$Equals(Scalar$create(99L)) # FALSE (types don't match)
+#' 
+#' my_scalar$ToString()
 #' @export
 Scalar <- R6Class("Scalar",
   inherit = ArrowDatum,