R: Read lines from a file

vroom_lines {vroom}

R Documentation

Read lines from a file

Description

vroom_lines() is similar to readLines(), however it reads the lines lazily like vroom(), so operations like length(), head(), tail() and sample() can be done much more efficiently without reading all the data into R.

Usage

vroom_lines(
  file,
  n_max = Inf,
  skip = 0,
  na = character(),
  skip_empty_rows = FALSE,
  locale = default_locale(),
  altrep = TRUE,
  altrep_opts = deprecated(),
  num_threads = vroom_threads(),
  progress = vroom_progress()
)

Arguments

`file`	path to a local file.
`n_max`	Maximum number of lines to read.
`skip`	Number of lines to skip before reading data. If `comment` is supplied any commented lines are ignored after skipping.
`na`	Character vector of strings to interpret as missing values. Set this option to `character()` to indicate no missing values.
`skip_empty_rows`	Should blank rows be ignored altogether? i.e. If this option is `TRUE` then blank rows will not be represented at all. If it is `FALSE` then they will be represented by `NA` values in all the columns.
`locale`	The locale controls defaults that vary from place to place. The default locale is US-centric (like R), but you can use `locale()` to create your own locale that controls things like the default time zone, encoding, decimal mark, big mark, and day/month names.
`altrep`	Control which column types use Altrep representations, either a character vector of types, `TRUE` or `FALSE`. See `vroom_altrep()` for for full details.
`altrep_opts`
`num_threads`	Number of threads to use when reading and materializing vectors. If your data contains newlines within fields the parser will automatically be forced to use a single thread only.
`progress`	Display a progress bar? By default it will only display in an interactive session and not while knitting a document. The automatic progress bar can be disabled by setting option `readr.show_progress` to `FALSE`.

Examples

lines <- vroom_lines(vroom_example("mtcars.csv"))

length(lines)
head(lines, n = 2)
tail(lines, n = 2)
sample(lines, size = 2)

[Package vroom version 1.5.7 Index]