vroom: vroom_lines – R documentation

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vroom_lines

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,
  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 records to read.
`skip`	Number of lines to skip before reading data.
`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 display is updated every 50,000 values and will only display if estimated reading time is 5 seconds or more. 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)

vroom

Read and Write Rectangular Text Data Quickly

v1.4.0

GPL-3

Authors

Jim Hester [aut, cre] (<https://orcid.org/0000-0002-2739-7082>), Hadley Wickham [aut] (<https://orcid.org/0000-0003-4757-117X>), https://github.com/mandreyel/ [cph] (mio library), R Core Team [ctb] (localtime.c code adapted from R), Jukka Jylänki [cph] (grisu3 implementation), Mikkel Jørgensen [cph] (grisu3 implementation), RStudio [cph, fnd]

Initial release