Recursively Apply a Function to a List

This helper function recursively iterates through a "list-like" object and it checks whether an element is of a given class. If it so, then it replaces that element by the result of an execution of a given function. Otherwise, and if the element is of length greater than 1 (i.e. not a scalar), it replaces that element by the result of h_rapply(), recursively called for that element. In the remaining case, that is, the element is not of a given class and is a scalar, then that element remains unchanged.

Usage

h_rapply(x, fun, classes, ...)

Arguments

x

(any)
"list-like" object for which subsetting operator [[ is defined.

fun

(function)
a function of one "principal" argument, passing further arguments via ....

classes

(character)
class names.

...

further arguments passed to function fun.

Value

"list-like" object of similar structure as x.

Note

This helper function is conceptually similar the same as rapply() function. However, it differs from rapply() in two major ways. First, the h_rapply() is not limited to objects of type list or expression only. It can be any "list-like" object of any type for which subsetting operator [[ is defined. This can be, for example, an object of type language, often obtained from the body() function. The second difference is that the flexibility of rapply() on how the result is structured is not available with h_rapply() for the user. That is, with h_rapply() each element of x, which has a class included in classes, is replaced by the result of applying fun to the element. This behavior corresponds to rapply() when invoked with fixed how = replace. This function was primarily designed as a helper for h_jags_write_model() function.

Examples

# Some model function.
my_model <- function() {
  alpha0 <- mean(1:10)
  alpha1 <- 600000
}

# Replace format of numbers using `formatC` function.
h_rapply(
  x = body(my_model),
  fun = formatC,
  classes = c("integer", "numeric"),
  digits = 3,
  format = "E"
)
#> {
#>     alpha0 <- mean("1.000E+00":"1.000E+01")
#>     alpha1 <- "6.000E+05"
#> }