Package 'fr'

Coerce a fr_tdr object into a data frame

Description

Equivalent to as.data.frame(); directly using tibble::as_tibble() also works because its input is first coerced with as.data.frame()

Usage

as_data_frame(x, ...)

Arguments

x	a fr_tdr object
...	ignored

Value

a data frame

Examples

as_fr_tdr(mtcars, name = "mtcars") |>
  as_data_frame()

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Coerce character, factor, numeric, logical, and Date vectors into fr_field objects

Description

The supported classes of R objects are converted to the corresponding frictionless type:

R class	fr type
character()	string
factor()	string (with enum(constraints = levels(x)))
numeric(), integer()	number
logical()	boolean
Date	date

Usage

as_fr_field(x, ...)

Arguments

x	a character, factor, numeric, integer, logical, or Date vector
...	<dynamic-dots> required (name) and optional (title, description) field descriptors)

Value

a fr_field object

Examples

as_fr_field(1:10, "example_integer") # -> frictionless number
as_fr_field((1:10) * 0.1, "example_double") # -> frictionless number
as_fr_field(letters, "example_character") # -> frictionless string
as_fr_field(factor(letters), "example_factor") # -> frictionless string with enum constraints
as_fr_field(c(TRUE, FALSE, TRUE), "example_logical") # -> frictionless boolean
as_fr_field(as.Date(c("2023-04-23", "2004-12-31")), "example_date") # -> frictionless date

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Coerce a data frame into a fr_tdr object

Description

Coerce a data frame into a fr_tdr object

Usage

as_fr_tdr(x, ...)

Arguments

x	a data.frame
...	<dynamic-dots> required (name) and optional tabular-data-resource properties (e.g., path, version, title, homepage, description)

Details

Use the .template argument to provide a template fr_tdr object from which table-specific (i.e. "name", "version", "title", "homepage", "description") and field-specific metadata will be copied; note that all metadata provided in ... will be ignored if this argument is provided

Value

a fr_tdr object

Examples

as_fr_tdr(mtcars, name = "mtcars")
S7::prop(as_fr_tdr(mtcars, name = "mtcars"), "schema")

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Coerce a fr_tdr object into a list

Description

equivalent to as.list()

Usage

as_list(x, ...)

Arguments

x	a fr_tdr object
...	ignored

Value

a list representing the frictionless metadata descriptor

Examples

as_fr_tdr(mtcars, name = "mtcars") |>
  as_list()

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dplyr methods for fr_tdr objects

Description

Some basic dplyr functions are re-implemented here for for fr_tdr objects. The input is converted with as.data.frame() before being passed to the dplyr function. The resulting tibble object is converted back into a fr_tdr object, matching table- and field-specific metadata where possible by using as_fr_tdr() and specifying the .template argument.  

dplyr	fr
mutate()	fr_mutate()
rename()	fr_rename()
select()	fr_select()
filter()	fr_filter()
summarise()	fr_summarise()
arrange()	fr_arrange()

Usage

fr_mutate(x, ...)

fr_rename(x, ...)

fr_select(x, ...)

fr_filter(x, ...)

fr_summarize(x, ...)

fr_arrange(x, ...)

Arguments

x	a fr_tdr object
...	passed to the underlying dplyr function

Value

a fr_tdr object

Examples

read_fr_tdr(fs::path_package("fr", "hamilton_poverty_2020")) |>
  fr_mutate(next_year = year + 1) |>
  fr_rename(new_year = next_year) |>
  fr_select(-new_year) |>
  fr_filter(fraction_poverty > 0.1) |>
  fr_summarize(median_poverty_fraction = median(fraction_poverty)) |>
  fr_arrange(median_poverty_fraction)

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Test if an object is a fr_field object

Description

Test if an object is a fr_field object

Usage

is_fr_field(x)

Arguments

x	an object to test

Value

TRUE if object is a fr_field object, FALSE otherwise

Examples

is_fr_field(letters)
is_fr_field(as_fr_field(letters, "letters"))

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read a tabular-data-resource into R

Description

read a tabular-data-resource into R

Usage

read_fr_tdr(file)

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().

Details

A file path (or url) representing a folder that contains a "tabular-data-resource.yaml" can be used in file.

Value

a fr_tdr object

Examples

read_fr_tdr(fs::path_package("fr", "hamilton_poverty_2020"))

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add or update field-specific metadata in a fr_tdr object

Description

add or update field-specific metadata in a fr_tdr object

Usage

update_field(x, field, ...)

Arguments

x	a fr_tdr object
field	character name of field in x to update
...	table schema field descriptors (e.g., title, description)

Value

an fr_tdr object containing the updated field

Examples

my_mtcars <-
  mtcars |>
  as_fr_tdr(name = "mtcars") |>
  update_field("mpg", title = "Miles Per Gallon")

S7::prop(my_mtcars, "schema")

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write a fr_tdr object to disk

Description

The name property of the fr_tdr object is used to write a frictionless tabular-data-resource to disk. For example, if name = "my_data", then a folder named my_data would be created with (1) my_data.csv and (2) tabular-data-resource.yaml.

Usage

write_fr_tdr(x, dir)

Arguments

x	a fr_tdr object to write to disk
dir	path to directory where tabular-data-resource folder will be created

Value

x (invisibly)

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