Read a CSV or other delimited file with Arrow

These functions uses the Arrow C++ CSV reader to read into a data.frame. Arrow C++ options have been mapped to argument names that follow those of readr::read_delim(), and col_select was inspired by vroom::vroom().

read_delim_arrow(
  file,
  delim = ",",
  quote = "\"",
  escape_double = TRUE,
  escape_backslash = FALSE,
  col_names = TRUE,
  col_select = NULL,
  na = c("", "NA"),
  quoted_na = TRUE,
  skip_empty_rows = TRUE,
  skip = 0L,
  parse_options = NULL,
  convert_options = NULL,
  read_options = NULL,
  as_data_frame = TRUE
)

read_csv_arrow(
  file,
  quote = "\"",
  escape_double = TRUE,
  escape_backslash = FALSE,
  col_names = TRUE,
  col_select = NULL,
  na = c("", "NA"),
  quoted_na = TRUE,
  skip_empty_rows = TRUE,
  skip = 0L,
  parse_options = NULL,
  convert_options = NULL,
  read_options = NULL,
  as_data_frame = TRUE
)

read_tsv_arrow(
  file,
  quote = "\"",
  escape_double = TRUE,
  escape_backslash = FALSE,
  col_names = TRUE,
  col_select = NULL,
  na = c("", "NA"),
  quoted_na = TRUE,
  skip_empty_rows = TRUE,
  skip = 0L,
  parse_options = NULL,
  convert_options = NULL,
  read_options = NULL,
  as_data_frame = TRUE
)

Arguments

file	A character file name, raw vector, or an Arrow input stream
delim	Single character used to separate fields within a record.
quote	Single character used to quote strings.
escape_double	Does the file escape quotes by doubling them? i.e. If this option is TRUE, the value """" represents a single quote, \".
escape_backslash	Does the file use backslashes to escape special characters? This is more general than escape_double as backslashes can be used to escape the delimiter character, the quote character, or to add special characters like \\n.
col_names	If TRUE, the first row of the input will be used as the column names and will not be included in the data frame. If FALSE, column names will be generated by Arrow, starting with "f0", "f1", ..., "fN". Alternatively, you can specify a character vector of column names.
col_select	A character vector of column names to keep, as in the "select" argument to data.table::fread(), or a tidy selection specification of columns, as used in dplyr::select().
na	A character vector of strings to interpret as missing values.
quoted_na	Should missing values inside quotes be treated as missing values (the default) or strings. (Note that this is different from the the Arrow C++ default for the corresponding convert option, strings_can_be_null.)
skip_empty_rows	Should blank rows be ignored altogether? If TRUE, blank rows will not be represented at all. If FALSE, they will be filled with missings.
skip	Number of lines to skip before reading data.
parse_options	see file reader options. If given, this overrides any parsing options provided in other arguments (e.g. delim, quote, etc.).
convert_options	see file reader options
read_options	see file reader options
as_data_frame	Should the function return a data.frame or an arrow::Table?

Value

A data.frame, or an Table if as_data_frame = FALSE.

Details

read_csv_arrow() and read_tsv_arrow() are wrappers around read_delim_arrow() that specify a delimiter.

Note that not all readr options are currently implemented here. Please file an issue if you encounter one that arrow should support.

If you need to control Arrow-specific reader parameters that don't have an equivalent in readr::read_csv(), you can either provide them in the parse_options, convert_options, or read_options arguments, or you can use CsvTableReader directly for lower-level access.

Examples

# \donttest{
  tf <- tempfile()
  on.exit(unlink(tf))
  write.csv(iris, file = tf)
  df <- read_csv_arrow(tf)
  dim(df)
#> [1] 150   6
  # Can select columns
  df <- read_csv_arrow(tf, col_select = starts_with("Sepal"))
# }