How to include (source) R script in other scripts

Question

I've created a utility R script, util.R, which I want to use from other scripts in my project. What is the proper way to ensure that the function this script defines are available to function in my other scripts?

I'm looking for something similar to the require function, that loads a package only if it has not been loaded yet. I don't want to call source("util.R") because that will load the script every time it is called.

I know that I will get some answers telling me to create a package, as in Organizing R Source Code :) But I'm not creating something that will be used elsewhere, it is just a standalone project.

I create packages for standalone projects all the time. It's not much work, and the benefits are huge. Go on, you know you want to do it... — Andrie, Jun 23 '11 at 15:27

score 102 · Accepted Answer · edited Sep 11 '15 at 08:03

102

Here is one possible way. Use the exists function to check for something unique in your util.R code.

For example:

if(!exists("foo", mode="function")) source("util.R")

(Edited to include mode="function", as Gavin Simpson pointed out)

edited Sep 11 '15 at 08:03

Roman

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answered Jun 23 '11 at 15:30

Andrie

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Nice use of `exists()` - needs `mode = "function"` adding to make it fool-proof – Gavin Simpson Jun 23 '11 at 16:05
1

`exists()` seems to throw an error except of returning one in R 3.0.2. – Michael Schubert Dec 05 '13 at 10:52
The correct usage is `exists("foo") and the answer was edited. – Andrie Feb 08 '15 at 20:06

score 18 · Answer 2 · answered Jun 23 '11 at 15:29

18

There is no such thing built-in, since R does not track calls to source and is not able to figure out what was loaded from where (this is not the case when using packages). Yet, you may use same idea as in C .h files, i.e. wrap the whole in:

if(!exists('util_R')){
 util_R<-T

 #Code

}

answered Jun 23 '11 at 15:29

mbq

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and then call `source("util.R")` within the `if` code, right? – rafalotufo Jun 23 '11 at 17:27
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@rafalotufo You would source("util.R") as usual. The code in mbq's post would go *into* util.R. You just put the entire body of what's in util.R right now into a giant if() statement, if that makes sense. – Keith Twombley May 16 '13 at 17:18

Gavin Simpson · Answer 3 · 2011-06-23T16:04:39.157

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Say util.R produces a function foo(). You can check if this function is available in the global environment and source the script if it isn't:

if(identical(length(ls(pattern = "^foo$")), 0))
    source("util.R")

That will find anything with the name foo. If you want to find a function, then (as mentioned by @Andrie) exists() is helpful but needs to be told exactly what type of object to look for, e.g.

if(exists("foo", mode = "function"))
    source("util.R")

Here is exists() in action:

> exists("foo", mode = "function")
[1] FALSE
> foo <- function(x) x
> exists("foo", mode = "function")
[1] TRUE
> rm(foo)
> foo <- 1:10
> exists("foo", mode = "function")
[1] FALSE

edited Jun 23 '11 at 16:04

answered Jun 23 '11 at 15:29

Gavin Simpson

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In this case, you may want to use `grepl(..., value=TRUE)` because your search term is probably not a regex. +1, by the way. – Andrie Jun 23 '11 at 15:32
?? `grepl()` doesn't have argument `value`, but I should probably fix the regexp in `ls()`... – Gavin Simpson Jun 23 '11 at 15:58
Sorry, my mistake. I meant `fixed=TRUE` – Andrie Jun 23 '11 at 16:01
@Andrie - Ah, OK. It didn't work anyway. Got dragged away whilst pondering this. `exists()` is better but I now see you have posted such an Answer in the meantime. – Gavin Simpson Jun 23 '11 at 16:07

score 5 · Answer 4 · answered May 16 '13 at 17:16

Here is a function I wrote. It wraps the base::source function to store a list of sourced files in a global environment list named sourced. It will only re-source a file if you provide a .force=TRUE argument to the call to source. Its argument signature is otherwise identical to the real source() so you don't need to rewrite your scripts to use this.

warning("overriding source with my own function FYI")
source <- function(path, .force=FALSE, ...) {
  library(tools)
  path <- tryCatch(normalizePath(path), error=function(e) path)
  m<-md5sum(path)

  go<-TRUE
  if (!is.vector(.GlobalEnv$sourced)) {
    .GlobalEnv$sourced <- list()
  }
  if(! is.null(.GlobalEnv$sourced[[path]])) {
    if(m == .GlobalEnv$sourced[[path]]) {
      message(sprintf("Not re-sourcing %s. Override with:\n  source('%s', .force=TRUE)", path, path))
      go<-FALSE
    }
    else {
      message(sprintf('re-sourcing %s as it has changed from: %s to: %s', path, .GlobalEnv$sourced[[path]], m))
      go<-TRUE
    }
  } 
  if(.force) {
    go<-TRUE
    message("  ...forcing.")
  }
  if(go) {
    message(sprintf("sourcing %s", path))
    .GlobalEnv$sourced[path] <- m
    base::source(path, ...)
  }
}

It's pretty chatty (lots of calls to message()) so you can take those lines out if you care. Any advice from veteran R users is appreciated; I'm pretty new to R.

score 5 · Answer 5 · answered Jun 23 '11 at 19:28

You could write a function that takes a filename and an environment name, checks to see if the file has been loaded into the environment and uses sys.source to source the file if not.

Here's a quick and untested function (improvements welcome!):

include <- function(file, env) {
  # ensure file and env are provided
  if(missing(file) || missing(env))
    stop("'file' and 'env' must be provided")
  # ensure env is character
  if(!is.character(file) || !is.character(env))
    stop("'file' and 'env' must be a character")

  # see if env is attached to the search path
  if(env %in% search()) {
    ENV <- get(env)
    files <- get(".files",ENV)
    # if the file hasn't been loaded
    if(!(file %in% files)) {
      sys.source(file, ENV)                        # load the file
      assign(".files", c(file, files), envir=ENV)  # set the flag
    }
  } else {
    ENV <- attach(NULL, name=env)      # create/attach new environment
    sys.source(file, ENV)              # load the file
    assign(".files", file, envir=ENV)  # set the flag
  }
}

score 0 · Answer 6 · answered May 28 '19 at 20:35

0

I solved my problem using entire address where my code is: Before:

if(!exists("foo", mode="function")) source("utils.r")

After:

if(!exists("foo", mode="function")) source("C:/tests/utils.r")

answered May 28 '19 at 20:35

José Roberto Ribeiro Filho

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How to include (source) R script in other scripts

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