Title here
Summary here
Generics in R Programming Language
# As an example of a generic function, `slices_index` takes
# a vector of any type and an element of that type and returns
# the index of the first occurrence of v in s, or -1 if not present.
# Note that R doesn't have built-in generics like Go, so we use
# base R functions to achieve similar functionality.
slices_index <- function(s, v) {
index <- match(v, s)
if (is.na(index)) {
return(-1)
}
return(index - 1) # R uses 1-based indexing, so we subtract 1 to match Go's 0-based indexing
}
# As an example of a generic type, we'll create a simple
# linked list structure using R's reference classes.
# This is not idiomatic R, but it demonstrates the concept.
List <- setRefClass("List",
fields = list(
head = "ANY",
tail = "ANY"
),
methods = list(
push = function(v) {
new_element <- list(val = v, next = NULL)
if (is.null(tail)) {
head <<- new_element
tail <<- head
} else {
tail$next <<- new_element
tail <<- tail$next
}
},
all_elements = function() {
elements <- c()
current <- head
while (!is.null(current)) {
elements <- c(elements, current$val)
current <- current$next
}
return(elements)
}
)
)
# Main function to demonstrate usage
main <- function() {
s <- c("foo", "bar", "zoo")
# When calling slices_index, we don't need to specify types
# as R is dynamically typed
cat("index of zoo:", slices_index(s, "zoo"), "\n")
lst <- List$new()
lst$push(10)
lst$push(13)
lst$push(23)
cat("list:", paste(lst$all_elements(), collapse = " "), "\n")
}
# Run the main function
main()This R code provides an equivalent implementation of the Go generics example. Here are some key points about the translation:
R doesn’t have built-in generics like Go, so we’ve used base R functions to achieve similar functionality in the
slices_indexfunction.For the
Listtype, we’ve used R’s reference classes to create a similar structure. This is not idiomatic R (which typically uses vectors or lists for such operations), but it demonstrates how you might implement a linked list in R.R is dynamically typed, so we don’t need to specify types explicitly as in Go. This means we don’t need type parameters in our function definitions.
R uses 1-based indexing, so we adjusted the
slices_indexfunction to return indices that match Go’s 0-based indexing.We’ve wrapped the main code in a
main()function to mimic the structure of the Go code, although this isn’t necessary in R.
To run this code, you would typically save it to a file (e.g., generics.R) and then run it using an R interpreter:
$ Rscript generics.R
index of zoo: 2
list: 10 13 23This example demonstrates how to implement generic-like functionality in R, even though R doesn’t have a direct equivalent to Go’s generics. It shows how to work with functions that can operate on different types and how to create custom data structures in R.