Extract parameter documentation from an R function help page
Source:R/parse_utils.R
get_documentation.RdReads the help page of a function and returns the descriptions of the parameters asked for, as plain text suitable for UI tooltips. Code is set in backticks and other Rd markup is reduced to its text.
Arguments
- package_name
A string in the format "package::function" indicating which function's documentation to parse.
- type
The type of documentation section to extract. Currently only "param" is supported.
- selected
A list of parameter names to extract. Co-documented parameters (e.g.,
x.byandy.by) can be grouped together in a vector within the list; each name gets the shared description.- cap
Logical; if TRUE, capitalize the first letter of each description.
Value
A named list where names are parameter names and values are their documentation strings. Returns empty strings for parameters not found in the documentation.
Details
Each package's help pages are read once per R session and kept, so building
a module's UI again (another tab, another dataset, another Figure Builder
panel) costs nothing. A package loaded with pkgload::load_all() is read
from its source man/ directory, so its own, current docs are used.
Examples
get_documentation("stats::lm", selected = list("formula", "data"), cap = TRUE)
#> $formula
#> [1] "An object of class `\"formula\"` (or one that can be coerced to that class): a symbolic description of the model to be fitted. The details of model specification are given under 'Details'."
#>
#> $data
#> [1] "An optional data frame, list or environment (or object coercible by `as.data.frame` to a data frame) containing the variables in the model. If not found in `data`, the variables are taken from `environment(formula)`, typically the environment from which `lm` is called."
#>