vroom: Read a delimited file into a tibble

In vroom: Read and Write Rectangular Text Data Quickly

Read a delimited file into a tibble

Description

Read a delimited file into a tibble

Usage

vroom(
  file,
  delim = NULL,
  col_names = TRUE,
  col_types = NULL,
  col_select = NULL,
  id = NULL,
  skip = 0,
  n_max = Inf,
  na = c("", "NA"),
  quote = "\"",
  comment = "",
  skip_empty_rows = TRUE,
  trim_ws = TRUE,
  escape_double = TRUE,
  escape_backslash = FALSE,
  locale = default_locale(),
  guess_max = 100,
  altrep = TRUE,
  altrep_opts = deprecated(),
  num_threads = vroom_threads(),
  progress = vroom_progress(),
  show_col_types = NULL,
  .name_repair = "unique"
)

Arguments

file	Either a path to a file, a connection, or literal data (either a single string or a raw vector). file can also be a character vector containing multiple filepaths or a list containing multiple connections. Files ending in .gz, .bz2, .xz, or .zip will be automatically uncompressed. Files starting with ⁠http://⁠, ⁠https://⁠, ⁠ftp://⁠, or ⁠ftps://⁠ will be automatically downloaded. Remote gz files can also be automatically downloaded and decompressed. Literal data is most useful for examples and tests. To be recognised as literal data, wrap the input with I().
delim	One or more characters used to delimit fields within a file. If NULL the delimiter is guessed from the set of c(",", "\t", " ", "|", ":", ";").
col_names	Either TRUE, FALSE or a character vector of column 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 automatically: X1, X2, X3 etc. If col_names is a character vector, the values will be used as the names of the columns, and the first row of the input will be read into the first row of the output data frame. Missing (NA) column names will generate a warning, and be filled in with dummy names ...1, ...2 etc. Duplicate column names will generate a warning and be made unique, see name_repair to control how this is done.
col_types	One of NULL, a cols() specification, or a string. If NULL, all column types will be imputed from guess_max rows on the input interspersed throughout the file. This is convenient (and fast), but not robust. If the imputation fails, you'll need to increase the guess_max or supply the correct types yourself. Column specifications created by list() or cols() must contain one column specification for each column. If you only want to read a subset of the columns, use cols_only(). Alternatively, you can use a compact string representation where each character represents one column: c = character i = integer n = number d = double l = logical f = factor D = date T = date time t = time ? = guess _ or - = skip By default, reading a file without a column specification will print a message showing what readr guessed they were. To remove this message, set show_col_types = FALSE or set options(readr.show_col_types = FALSE).
col_select	Columns to include in the results. You can use the same mini-language as dplyr::select() to refer to the columns by name. Use c() to use more than one selection expression. Although this usage is less common, col_select also accepts a numeric column index. See ?tidyselect::language for full details on the selection language.
id	Either a string or 'NULL'. If a string, the output will contain a variable with that name with the filename(s) as the value. If 'NULL', the default, no variable will be created.
skip	Number of lines to skip before reading data. If comment is supplied any commented lines are ignored after skipping.
n_max	Maximum number of lines to read.
na	Character vector of strings to interpret as missing values. Set this option to character() to indicate no missing values.
quote	Single character used to quote strings.
comment	A string used to identify comments. Any text after the comment characters will be silently ignored.
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.
trim_ws	Should leading and trailing whitespace (ASCII spaces and tabs) be trimmed from each field before parsing it?
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.
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.
guess_max	Maximum number of lines to use for guessing column types. See vignette("column-types", package = "readr") for more details.
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	\Sexpr[results=rd, stage=render]{lifecycle::badge("deprecated")}
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.
show_col_types	Control showing the column specifications. If TRUE column specifications are always show, if FALSE they are never shown. If NULL (the default) they are shown only if an explicit specification is not given to col_types.
.name_repair	Handling of column names. The default behaviour is to ensure column names are "unique". Various repair strategies are supported: "minimal": No name repair or checks, beyond basic existence of names. "unique" (default value): Make sure names are unique and not empty. "check_unique": no name repair, but check they are unique. "universal": Make the names unique and syntactic. A function: apply custom name repair (e.g., name_repair = make.names for names in the style of base R). A purrr-style anonymous function, see rlang::as_function(). This argument is passed on as repair to vctrs::vec_as_names(). See there for more details on these terms and the strategies used to enforce them.

Examples

# get path to example file
input_file <- vroom_example("mtcars.csv")
input_file

# Read from a path

# Input sources -------------------------------------------------------------
# Read from a path
vroom(input_file)
# You can also use paths directly
# vroom("mtcars.csv")

## Not run: 
# Including remote paths
vroom("https://github.com/tidyverse/vroom/raw/main/inst/extdata/mtcars.csv")

## End(Not run)

# Or directly from a string with `I()`
vroom(I("x,y\n1,2\n3,4\n"))

# Column selection ----------------------------------------------------------
# Pass column names or indexes directly to select them
vroom(input_file, col_select = c(model, cyl, gear))
vroom(input_file, col_select = c(1, 3, 11))

# Or use the selection helpers
vroom(input_file, col_select = starts_with("d"))

# You can also rename specific columns
vroom(input_file, col_select = c(car = model, everything()))

# Column types --------------------------------------------------------------
# By default, vroom guesses the columns types, looking at 1000 rows
# throughout the dataset.
# You can specify them explicitly with a compact specification:
vroom(I("x,y\n1,2\n3,4\n"), col_types = "dc")

# Or with a list of column types:
vroom(I("x,y\n1,2\n3,4\n"), col_types = list(col_double(), col_character()))

# File types ----------------------------------------------------------------
# csv
vroom(I("a,b\n1.0,2.0\n"), delim = ",")
# tsv
vroom(I("a\tb\n1.0\t2.0\n"))
# Other delimiters
vroom(I("a|b\n1.0|2.0\n"), delim = "|")

# Read datasets across multiple files ---------------------------------------
mtcars_by_cyl <- vroom_example(vroom_examples("mtcars-"))
mtcars_by_cyl

# Pass the filenames directly to vroom, they are efficiently combined
vroom(mtcars_by_cyl)

# If you need to extract data from the filenames, use `id` to request a
# column that reveals the underlying file path
dat <- vroom(mtcars_by_cyl, id = "source")
dat$source <- basename(dat$source)
dat

vroom documentation built on July 4, 2024, 9:08 a.m.