USING.md

Using

To run R code you must install R and have the R executable on your PATH. You can download R from their site.

To use this extension, you must first include it at the top of your NetLogo model code in an extensions declaration.

extensions [
  sr
  ; ... your other extensions
]

You must then initialize the R environment with sr:setup. This only needs to be done once per session. Any subsequent calls will reset your R environment.

Here's an example to get you started:

observer> sr:setup
;; sr:runresult evaluates R statements and returns the result back to NetLogo
observer> show sr:runresult "2 + 2"
observer: 4
;; sr:run runs R code
observer> sr:run "cat('hello world')"
hello world
;; any standard output gets forwarded to the command center output
;; sr:set sets R variables to values from NetLogo
observer> ask patch 0 0 [ set pcolor red ]
observer> sr:set "center_patch_color" [pcolor] of patch 0 0
observer> show sr:runresult "center_patch_color"
observer: 15 ;; the NetLogo representation of the color red

See the documentation for each of the particular primitives for details on, for instance, how to multi-line statements and how object type conversions work.

The extension also includes an interactive R console/REPL that is connected to the same R environment as the main window's NetLogo environment. It is useful for executing longer blocks of R code or quickly examining or modifying R values. This console can be opened via the menu bar under the SimpleR heading, or by using the sr:show-console command.

Error handling

R errors will be reported in NetLogo as "Extension exceptions". For instance, this code:

sr:run "stop('hi')"

will result in the NetLogo error "Extension exception: hi" appearing in an error dialog.