read_csv()
and read_tsv()
are special cases of the more general
read_delim()
. They're useful for reading the most common types of
flat file data, comma separated values and tab separated values,
respectively. read_csv2()
uses ;
for the field separator and ,
for the
decimal point. This format is common in some European countries.
Usage
read_delim(
file,
delim = NULL,
quote = "\"",
escape_backslash = FALSE,
escape_double = TRUE,
col_names = TRUE,
col_types = NULL,
col_select = NULL,
id = NULL,
locale = default_locale(),
na = c("", "NA"),
quoted_na = TRUE,
comment = "",
trim_ws = FALSE,
skip = 0,
n_max = Inf,
guess_max = min(1000, n_max),
name_repair = "unique",
num_threads = readr_threads(),
progress = show_progress(),
show_col_types = should_show_types(),
skip_empty_rows = TRUE,
lazy = should_read_lazy()
)
read_csv(
file,
col_names = TRUE,
col_types = NULL,
col_select = NULL,
id = NULL,
locale = default_locale(),
na = c("", "NA"),
quoted_na = TRUE,
quote = "\"",
comment = "",
trim_ws = TRUE,
skip = 0,
n_max = Inf,
guess_max = min(1000, n_max),
name_repair = "unique",
num_threads = readr_threads(),
progress = show_progress(),
show_col_types = should_show_types(),
skip_empty_rows = TRUE,
lazy = should_read_lazy()
)
read_csv2(
file,
col_names = TRUE,
col_types = NULL,
col_select = NULL,
id = NULL,
locale = default_locale(),
na = c("", "NA"),
quoted_na = TRUE,
quote = "\"",
comment = "",
trim_ws = TRUE,
skip = 0,
n_max = Inf,
guess_max = min(1000, n_max),
progress = show_progress(),
name_repair = "unique",
num_threads = readr_threads(),
show_col_types = should_show_types(),
skip_empty_rows = TRUE,
lazy = should_read_lazy()
)
read_tsv(
file,
col_names = TRUE,
col_types = NULL,
col_select = NULL,
id = NULL,
locale = default_locale(),
na = c("", "NA"),
quoted_na = TRUE,
quote = "\"",
comment = "",
trim_ws = TRUE,
skip = 0,
n_max = Inf,
guess_max = min(1000, n_max),
progress = show_progress(),
name_repair = "unique",
num_threads = readr_threads(),
show_col_types = should_show_types(),
skip_empty_rows = TRUE,
lazy = should_read_lazy()
)
Arguments
- file
Either a path to a file, a connection, or literal data (either a single string or a raw vector).
Files ending in
.gz
,.bz2
,.xz
, or.zip
will be automatically uncompressed. Files starting withhttp://
,https://
,ftp://
, orftps://
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, the input must be either wrapped with
I()
, be a string containing at least one new line, or be a vector containing at least one string with a new line.Using a value of
clipboard()
will read from the system clipboard.- delim
Single character used to separate fields within a record.
- quote
Single character used to quote strings.
- 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
.- escape_double
Does the file escape quotes by doubling them? i.e. If this option is
TRUE
, the value""""
represents a single quote,\"
.- 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. IfFALSE
, 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, seename_repair
to control how this is done.- col_types
One of
NULL
, acols()
specification, or a string. Seevignette("readr")
for more details.If
NULL
, all column types will be inferred fromguess_max
rows of the input, interspersed throughout the file. This is convenient (and fast), but not robust. If the guessed types are wrong, you'll need to increaseguess_max
or supply the correct types yourself.Column specifications created by
list()
orcols()
must contain one column specification for each column. If you only want to read a subset of the columns, usecols_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, setshow_col_types = FALSE
or setoptions(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. Usec()
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
The name of a column in which to store the file path. This is useful when reading multiple input files and there is data in the file paths, such as the data collection date. If
NULL
(the default) no extra column is created.- 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.- na
Character vector of strings to interpret as missing values. Set this option to
character()
to indicate no missing values.- quoted_na
Should missing values inside quotes be treated as missing values (the default) or strings. This parameter is soft deprecated as of readr 2.0.0.
- comment
A string used to identify comments. Any text after the comment characters will be silently ignored.
- trim_ws
Should leading and trailing whitespace (ASCII spaces and tabs) be trimmed from each field before parsing it?
- 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.
- guess_max
Maximum number of lines to use for guessing column types. Will never use more than the number of lines read. See
vignette("column-types", package = "readr")
for more details.- 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 areunique
."unique_quiet"
: Repair with theunique
strategy, quietly."universal"
: Make the namesunique
and syntactic."universal_quiet"
: Repair with theuniversal
strategy, quietly.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
tovctrs::vec_as_names()
. See there for more details on these terms and the strategies used to enforce them.- num_threads
The number of processing threads to use for initial parsing and lazy reading of data. If your data contains newlines within fields the parser should automatically detect this and fall back to using one thread only. However if you know your file has newlines within quoted fields it is safest to set
num_threads = 1
explicitly.- 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
toFALSE
.- show_col_types
If
FALSE
, do not show the guessed column types. IfTRUE
always show the column types, even if they are supplied. IfNULL
(the default) only show the column types if they are not explicitly supplied by thecol_types
argument.- 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 isFALSE
then they will be represented byNA
values in all the columns.- lazy
Read values lazily? By default, this is
FALSE
, because there are special considerations when reading a file lazily that have tripped up some users. Specifically, things get tricky when reading and then writing back into the same file. But, in general, lazy reading (lazy = TRUE
) has many benefits, especially for interactive use and when your downstream work only involves a subset of the rows or columns.Learn more in
should_read_lazy()
and in the documentation for thealtrep
argument ofvroom::vroom()
.
Value
A tibble()
. If there are parsing problems, a warning will alert you.
You can retrieve the full details by calling problems()
on your dataset.
Examples
# Input sources -------------------------------------------------------------
# Read from a path
read_csv(readr_example("mtcars.csv"))
#> Rows: 32 Columns: 11
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> dbl (11): mpg, cyl, disp, hp, drat, wt, qsec, vs, am, gear, carb
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 32 × 11
#> mpg cyl disp hp drat wt qsec vs am gear carb
#> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 21 6 160 110 3.9 2.62 16.5 0 1 4 4
#> 2 21 6 160 110 3.9 2.88 17.0 0 1 4 4
#> 3 22.8 4 108 93 3.85 2.32 18.6 1 1 4 1
#> 4 21.4 6 258 110 3.08 3.22 19.4 1 0 3 1
#> 5 18.7 8 360 175 3.15 3.44 17.0 0 0 3 2
#> 6 18.1 6 225 105 2.76 3.46 20.2 1 0 3 1
#> 7 14.3 8 360 245 3.21 3.57 15.8 0 0 3 4
#> 8 24.4 4 147. 62 3.69 3.19 20 1 0 4 2
#> 9 22.8 4 141. 95 3.92 3.15 22.9 1 0 4 2
#> 10 19.2 6 168. 123 3.92 3.44 18.3 1 0 4 4
#> # ℹ 22 more rows
read_csv(readr_example("mtcars.csv.zip"))
#> Rows: 32 Columns: 11
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> dbl (11): mpg, cyl, disp, hp, drat, wt, qsec, vs, am, gear, carb
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 32 × 11
#> mpg cyl disp hp drat wt qsec vs am gear carb
#> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 21 6 160 110 3.9 2.62 16.5 0 1 4 4
#> 2 21 6 160 110 3.9 2.88 17.0 0 1 4 4
#> 3 22.8 4 108 93 3.85 2.32 18.6 1 1 4 1
#> 4 21.4 6 258 110 3.08 3.22 19.4 1 0 3 1
#> 5 18.7 8 360 175 3.15 3.44 17.0 0 0 3 2
#> 6 18.1 6 225 105 2.76 3.46 20.2 1 0 3 1
#> 7 14.3 8 360 245 3.21 3.57 15.8 0 0 3 4
#> 8 24.4 4 147. 62 3.69 3.19 20 1 0 4 2
#> 9 22.8 4 141. 95 3.92 3.15 22.9 1 0 4 2
#> 10 19.2 6 168. 123 3.92 3.44 18.3 1 0 4 4
#> # ℹ 22 more rows
read_csv(readr_example("mtcars.csv.bz2"))
#> Rows: 32 Columns: 11
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> dbl (11): mpg, cyl, disp, hp, drat, wt, qsec, vs, am, gear, carb
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 32 × 11
#> mpg cyl disp hp drat wt qsec vs am gear carb
#> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl> <dbl>
#> 1 21 6 160 110 3.9 2.62 16.5 0 1 4 4
#> 2 21 6 160 110 3.9 2.88 17.0 0 1 4 4
#> 3 22.8 4 108 93 3.85 2.32 18.6 1 1 4 1
#> 4 21.4 6 258 110 3.08 3.22 19.4 1 0 3 1
#> 5 18.7 8 360 175 3.15 3.44 17.0 0 0 3 2
#> 6 18.1 6 225 105 2.76 3.46 20.2 1 0 3 1
#> 7 14.3 8 360 245 3.21 3.57 15.8 0 0 3 4
#> 8 24.4 4 147. 62 3.69 3.19 20 1 0 4 2
#> 9 22.8 4 141. 95 3.92 3.15 22.9 1 0 4 2
#> 10 19.2 6 168. 123 3.92 3.44 18.3 1 0 4 4
#> # ℹ 22 more rows
if (FALSE) { # \dontrun{
# Including remote paths
read_csv("https://github.com/tidyverse/readr/raw/main/inst/extdata/mtcars.csv")
} # }
# Read from multiple file paths at once
continents <- c("africa", "americas", "asia", "europe", "oceania")
filepaths <- vapply(
paste0("mini-gapminder-", continents, ".csv"),
FUN = readr_example,
FUN.VALUE = character(1)
)
read_csv(filepaths, id = "file")
#> Rows: 26 Columns: 6
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> chr (1): country
#> dbl (4): year, lifeExp, pop, gdpPercap
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 26 × 6
#> file country year lifeExp pop gdpPercap
#> <chr> <chr> <dbl> <dbl> <dbl> <dbl>
#> 1 /home/runner/work/_temp/Library… Algeria 1952 43.1 9.28e6 2449.
#> 2 /home/runner/work/_temp/Library… Angola 1952 30.0 4.23e6 3521.
#> 3 /home/runner/work/_temp/Library… Benin 1952 38.2 1.74e6 1063.
#> 4 /home/runner/work/_temp/Library… Botswa… 1952 47.6 4.42e5 851.
#> 5 /home/runner/work/_temp/Library… Burkin… 1952 32.0 4.47e6 543.
#> 6 /home/runner/work/_temp/Library… Burundi 1952 39.0 2.45e6 339.
#> 7 /home/runner/work/_temp/Library… Argent… 1952 62.5 1.79e7 5911.
#> 8 /home/runner/work/_temp/Library… Bolivia 1952 40.4 2.88e6 2677.
#> 9 /home/runner/work/_temp/Library… Brazil 1952 50.9 5.66e7 2109.
#> 10 /home/runner/work/_temp/Library… Canada 1952 68.8 1.48e7 11367.
#> # ℹ 16 more rows
# Or directly from a string with `I()`
read_csv(I("x,y\n1,2\n3,4"))
#> Rows: 2 Columns: 2
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> dbl (2): x, y
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 2 × 2
#> x y
#> <dbl> <dbl>
#> 1 1 2
#> 2 3 4
# Column selection-----------------------------------------------------------
# Pass column names or indexes directly to select them
read_csv(readr_example("chickens.csv"), col_select = c(chicken, eggs_laid))
#> Rows: 5 Columns: 2
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> chr (1): chicken
#> dbl (1): eggs_laid
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 5 × 2
#> chicken eggs_laid
#> <chr> <dbl>
#> 1 Foghorn Leghorn 0
#> 2 Chicken Little 3
#> 3 Ginger 12
#> 4 Camilla the Chicken 7
#> 5 Ernie The Giant Chicken 0
read_csv(readr_example("chickens.csv"), col_select = c(1, 3:4))
#> Rows: 5 Columns: 3
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> chr (2): chicken, motto
#> dbl (1): eggs_laid
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 5 × 3
#> chicken eggs_laid motto
#> <chr> <dbl> <chr>
#> 1 Foghorn Leghorn 0 That's a joke, ah say, that's a joke,…
#> 2 Chicken Little 3 The sky is falling!
#> 3 Ginger 12 Listen. We'll either die free chicken…
#> 4 Camilla the Chicken 7 Bawk, buck, ba-gawk.
#> 5 Ernie The Giant Chicken 0 Put Captain Solo in the cargo hold.
# Or use the selection helpers
read_csv(
readr_example("chickens.csv"),
col_select = c(starts_with("c"), last_col())
)
#> Rows: 5 Columns: 2
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> chr (2): chicken, motto
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 5 × 2
#> chicken motto
#> <chr> <chr>
#> 1 Foghorn Leghorn That's a joke, ah say, that's a joke, son.
#> 2 Chicken Little The sky is falling!
#> 3 Ginger Listen. We'll either die free chickens or we di…
#> 4 Camilla the Chicken Bawk, buck, ba-gawk.
#> 5 Ernie The Giant Chicken Put Captain Solo in the cargo hold.
# You can also rename specific columns
read_csv(
readr_example("chickens.csv"),
col_select = c(egg_yield = eggs_laid, everything())
)
#> Rows: 5 Columns: 4
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> chr (3): chicken, sex, motto
#> dbl (1): eggs_laid
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 5 × 4
#> egg_yield chicken sex motto
#> <dbl> <chr> <chr> <chr>
#> 1 0 Foghorn Leghorn rooster That's a joke, ah say, that's…
#> 2 3 Chicken Little hen The sky is falling!
#> 3 12 Ginger hen Listen. We'll either die free…
#> 4 7 Camilla the Chicken hen Bawk, buck, ba-gawk.
#> 5 0 Ernie The Giant Chicken rooster Put Captain Solo in the cargo…
# Column types --------------------------------------------------------------
# By default, readr guesses the columns types, looking at `guess_max` rows.
# You can override with a compact specification:
read_csv(I("x,y\n1,2\n3,4"), col_types = "dc")
#> # A tibble: 2 × 2
#> x y
#> <dbl> <chr>
#> 1 1 2
#> 2 3 4
# Or with a list of column types:
read_csv(I("x,y\n1,2\n3,4"), col_types = list(col_double(), col_character()))
#> # A tibble: 2 × 2
#> x y
#> <dbl> <chr>
#> 1 1 2
#> 2 3 4
# If there are parsing problems, you get a warning, and can extract
# more details with problems()
y <- read_csv(I("x\n1\n2\nb"), col_types = list(col_double()))
#> Warning: One or more parsing issues, call `problems()` on your data frame for
#> details, e.g.:
#> dat <- vroom(...)
#> problems(dat)
y
#> # A tibble: 3 × 1
#> x
#> <dbl>
#> 1 1
#> 2 2
#> 3 NA
problems(y)
#> # A tibble: 1 × 5
#> row col expected actual file
#> <int> <int> <chr> <chr> <chr>
#> 1 4 1 a double b /tmp/Rtmpqy3PHW/file16e42dd33614
# Column names --------------------------------------------------------------
# By default, readr duplicate name repair is noisy
read_csv(I("x,x\n1,2\n3,4"))
#> New names:
#> • `x` -> `x...1`
#> • `x` -> `x...2`
#> Rows: 2 Columns: 2
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> dbl (2): x...1, x...2
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 2 × 2
#> x...1 x...2
#> <dbl> <dbl>
#> 1 1 2
#> 2 3 4
# Same default repair strategy, but quiet
read_csv(I("x,x\n1,2\n3,4"), name_repair = "unique_quiet")
#> Rows: 2 Columns: 2
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> dbl (2): x...1, x...2
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 2 × 2
#> x...1 x...2
#> <dbl> <dbl>
#> 1 1 2
#> 2 3 4
# There's also a global option that controls verbosity of name repair
withr::with_options(
list(rlib_name_repair_verbosity = "quiet"),
read_csv(I("x,x\n1,2\n3,4"))
)
#> Rows: 2 Columns: 2
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> dbl (2): x...1, x...2
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 2 × 2
#> x...1 x...2
#> <dbl> <dbl>
#> 1 1 2
#> 2 3 4
# Or use "minimal" to turn off name repair
read_csv(I("x,x\n1,2\n3,4"), name_repair = "minimal")
#> Rows: 2 Columns: 2
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> dbl (2): x, x
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 2 × 2
#> x x
#> <dbl> <dbl>
#> 1 1 2
#> 2 3 4
# File types ----------------------------------------------------------------
read_csv(I("a,b\n1.0,2.0"))
#> Rows: 1 Columns: 2
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ","
#> dbl (2): a, b
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 1 × 2
#> a b
#> <dbl> <dbl>
#> 1 1 2
read_csv2(I("a;b\n1,0;2,0"))
#> ℹ Using "','" as decimal and "'.'" as grouping mark. Use `read_delim()` for more control.
#> Rows: 1 Columns: 2
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: ";"
#> dbl (2): a, b
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 1 × 2
#> a b
#> <dbl> <dbl>
#> 1 1 2
read_tsv(I("a\tb\n1.0\t2.0"))
#> Rows: 1 Columns: 2
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: "\t"
#> dbl (2): a, b
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 1 × 2
#> a b
#> <dbl> <dbl>
#> 1 1 2
read_delim(I("a|b\n1.0|2.0"), delim = "|")
#> Rows: 1 Columns: 2
#> ── Column specification ──────────────────────────────────────────────────
#> Delimiter: "|"
#> dbl (2): a, b
#>
#> ℹ Use `spec()` to retrieve the full column specification for this data.
#> ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.
#> # A tibble: 1 × 2
#> a b
#> <dbl> <dbl>
#> 1 1 2