inject string at %(variable)s in R (Url pattern) -

i tryning build kind of rest full api comunicate r. got issue replacement of strings.

i've got url path as:

http://localhost:8000/rest/api/model/%(id)s/model_function 

i need replace "%(id)s" model's id. function python stuff:

function(url, list(id=[id_value]) 

returning...

http://localhost:8000/rest/api/model/[id_value]/model_function 

any tips around? implement string replacement:

substitute_url_args <- function(url, list_args){   replace_names <- paste("%(",names(list_args),")s", sep="")<br>   <- 1   (i in 1:length(names(list_args))) {     url <- sub(replace_names[i], list_args[[i]], url, fixed=true)   }   return(url) } 

sure not elegant solution!

thanks in advance,

andré

try gsubfn in gsubfn package:

library(gsubfn)  substitute_url_args <- function(url, list_args) {   gsubfn("%\\((.*?)\\)s", x = url, env = list_args) }  # test s <- "http://localhost:8000/rest/api/model/%(id)s/model_function" l <- list(id = "[model_value]")  substitute_url_args(s, l) ## [1] "http://localhost:8000/rest/api/model/[model_value]/model_function" 

note if in control of , can specify backquotes surround substitutions easier:

substitute_url_args2 <- function(url, list_args) {   gsubfn(x = url, env = list_args) }  # test - l above ss <- "http://localhost:8000/rest/api/model/`id`/model_function"  substitute_url_args2(ss, l) ## [1] "http://localhost:8000/rest/api/model/[model_value]/model_function" 

note 2 if knew there 1 variable replace done using sub this:

substitute_url_args3 <- function(url, list_args) {   stopifnot(length(list_args) == 1)   sub("%\\(.*?\\)s", list_args[[1]], url) }  # test - s , l above substitute_url_args3(s, l) ## [1] "http://localhost:8000/rest/api/model/[model_value]/model_function"