arrow (version 0.17.1)

read_delim_arrow: Read a CSV or other delimited file with Arrow

Description

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().

Usage

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 (default) or an Arrow Table?

Value

A data.frame, or a 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

# NOT RUN {
  tf <- tempfile()
  on.exit(unlink(tf))
  write.csv(iris, file = tf)
  df <- read_csv_arrow(tf)
  dim(df)
  # Can select columns
  df <- read_csv_arrow(tf, col_select = starts_with("Sepal"))
# }