Casting Values into Shape

Helper functions with a consistent interface to coerce and verify the types and shapes of values for input checking.


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forge provides functions for input checking and casting. It is intended to be used by package developers, especially for interoperating with other runtimes, such as Python and JVM languages. It contains two families of functions, cast_* and certify(). The former casts a value to a specific type, while the latter ensures certain conditions are met.

Installation

You can install forge from CRAN with

install.packages("forge")

You can install the development version from GitHub with

devtools::install_github("rstudio/forge")

Examples

Here we demonstrate forge with a trivial function:

#' @import forge
fib <- function(n) {
  n <- cast_scalar_integer(n, return_id = TRUE) %>%
    certify(gte(0))
  
  if (n <= 2) {
    if( n >= 0) 1 else 0 
  } else {
    Recall(n - 1) + Recall(n - 2)
  }
}
fib(10)
#> [1] 55
fib(1.5)
#> Error: `n` cannot be casted to an integer vector.
fib(-2)
#> Error: Condition `gte(0)` not satisfied for `n`.

We can also provide arbitrary conditions to certify():

some_vec <- 1:5
certify(some_vec,  ~ any(.x < 2))
#> [1] 1 2 3 4 5
certify(some_vec, ~ mean(.x) > 2)
#> [1] 1 2 3 4 5
certify(some_vec, ~ all(.x <= 5), ~ mean(.x) > 3)
#> Error: Condition `~mean(.x) > 3` not satisfied for `some_vec`.

Please note that the ‘forge’ project is released with a Contributor Code of Conduct. By contributing to this project, you agree to abide by its terms.

News

forge 0.2.0

  • All function gained an id parameter for the developer to specify a name for the input. This defaults to the developer inputed expression for x. The return_id parameter can be set when using the %>% operator to pass the ID to the next forge function.
  • Added certify() along with helper functions e.g. ge(), gte(), lt(), for common comparisons. One can also provide arbitrary conditions in the form of functions.
  • Revised README to reflect changes.

Reference manual

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install.packages("forge")

0.2.0 by Kevin Kuo, 4 months ago


Browse source code at https://github.com/cran/forge


Authors: Kevin Kuo [aut, cre]


Documentation:   PDF Manual  


Apache License (>= 2.0) license


Imports rlang, magrittr

Suggests testthat, covr


Imported by graphframes, mlflow, sparklyr, sparkxgb, tfestimators, tfio.


See at CRAN