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.
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()
)
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 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, 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.
Single character used to separate fields within a record.
Single character used to quote strings.
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
.
Does the file escape quotes by doubling them?
i.e. If this option is TRUE
, the value """"
represents
a single quote, \"
.
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.
One of NULL
, a cols()
specification, or
a string. See vignette("readr")
for more details.
If NULL
, all column types will be inferred from guess_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 increase
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)
.
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.
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.
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.
Character vector of strings to interpret as missing values. Set this
option to character()
to indicate no missing values.
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.
A string used to identify comments. Any text after the comment characters will be silently ignored.
Should leading and trailing whitespace (ASCII spaces and tabs) be trimmed from each field before parsing it?
Number of lines to skip before reading data. If comment
is
supplied any commented lines are ignored after skipping.
Maximum number of lines to read.
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.
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
.
"unique_quiet"
: Repair with the unique
strategy, quietly.
"universal"
: Make the names unique
and syntactic.
"universal_quiet"
: Repair with the universal
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
to vctrs::vec_as_names()
.
See there for more details on these terms and the strategies used
to enforce them.
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.
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
.
If FALSE
, do not show the guessed column types. If
TRUE
always show the column types, even if they are supplied. If NULL
(the default) only show the column types if they are not explicitly supplied
by the col_types
argument.
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.
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 the
altrep
argument of vroom::vroom()
.
A tibble()
. If there are parsing problems, a warning will alert you.
You can retrieve the full details by calling problems()
on your dataset.
# 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 /tmp/RtmpjLk82K/temp_libpath23d005308… Algeria 1952 43.1 9.28e6 2449.
#> 2 /tmp/RtmpjLk82K/temp_libpath23d005308… Angola 1952 30.0 4.23e6 3521.
#> 3 /tmp/RtmpjLk82K/temp_libpath23d005308… Benin 1952 38.2 1.74e6 1063.
#> 4 /tmp/RtmpjLk82K/temp_libpath23d005308… Botswa… 1952 47.6 4.42e5 851.
#> 5 /tmp/RtmpjLk82K/temp_libpath23d005308… Burkin… 1952 32.0 4.47e6 543.
#> 6 /tmp/RtmpjLk82K/temp_libpath23d005308… Burundi 1952 39.0 2.45e6 339.
#> 7 /tmp/RtmpjLk82K/temp_libpath23d005308… Argent… 1952 62.5 1.79e7 5911.
#> 8 /tmp/RtmpjLk82K/temp_libpath23d005308… Bolivia 1952 40.4 2.88e6 2677.
#> 9 /tmp/RtmpjLk82K/temp_libpath23d005308… Brazil 1952 50.9 5.66e7 2109.
#> 10 /tmp/RtmpjLk82K/temp_libpath23d005308… 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, son.
#> 2 Chicken Little 3 The sky is falling!
#> 3 Ginger 12 Listen. We'll either die free chickens or w…
#> 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 die tryi…
#> 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 a jok…
#> 2 3 Chicken Little hen The sky is falling!
#> 3 12 Ginger hen Listen. We'll either die free chick…
#> 4 7 Camilla the Chicken hen Bawk, buck, ba-gawk.
#> 5 0 Ernie The Giant Chicken rooster Put Captain Solo in the cargo hold.
# 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/RtmprSQVR5/file23f8c9e9324c7
# 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