File reader options

Description

CsvReadOptions, CsvParseOptions, CsvConvertOptions, JsonReadOptions, and JsonParseOptions are containers for various file reading options. See their usage in read_csv_arrow() and read_json_arrow(), respectively.

Factory

The CsvReadOptions$create() and JsonReadOptions$create() factory methods take the following arguments:

• use_threads Whether to use the global CPU thread pool

• block_size Block size we request from the IO layer; also determines the size of chunks when use_threads is TRUE. NB: if FALSE, JSON input must end with an empty line.

CsvReadOptions$create() further accepts these additional arguments:

• skip_rows Number of lines to skip before reading data (default 0)

• column_names Character vector to supply column names. If length-0 (the default), the first non-skipped row will be parsed to generate column names, unless autogenerate_column_names is TRUE.

• autogenerate_column_names Logical: generate column names instead of using the first non-skipped row (the default)? If TRUE, column names will be "f0", "f1", ..., "fN".

CsvParseOptions$create() takes the following arguments:

• delimiter Field delimiting character (default ",")

• quoting Logical: are strings quoted? (default TRUE)

• quote_char Quoting character, if quoting is TRUE

• double_quote Logical: are quotes inside values double-quoted? (default TRUE)

• escaping Logical: whether escaping is used (default FALSE)

• escape_char Escaping character, if escaping is TRUE

• newlines_in_values Logical: are values allowed to contain CR (0x0d) and LF (0x0a) characters? (default FALSE)

• ignore_empty_lines Logical: should empty lines be ignored (default) or generate a row of missing values (if FALSE)?

JsonParseOptions$create() accepts only the newlines_in_values argument.

CsvConvertOptions$create() takes the following arguments:

• check_utf8 Logical: check UTF8 validity of string columns? (default TRUE)

• null_values character vector of recognized spellings for null values. Analogous to the na.strings argument to read.csv() or na in readr::read_csv().

• strings_can_be_null Logical: can string / binary columns have null values? Similar to the quoted_na argument to readr::read_csv(). (default FALSE)

Methods

These classes have no implemented methods. They are containers for the options.