clojure.md

Calling R from within Clojure

Clojure is one of the most popular JVM languages. RCaller can directly be used in a Clojure project. Firstly, add the RCaller dependency in your project.clj file:

:dependencies [[org.clojure/clojure "1.10.1"]
                 [com.github.jbytecode/RCaller "3.0.2"]]

The primary Java classes RCaller and RCode can be included in the project using

(ns rcallertest.core
  (:import [com.github.rcaller.rstuff RCaller RCode])
  (:gen-class))

RCaller interacts with R interpreter in two ways. The first one simply passes the R code and gets back the calculated results. The R process is terminated after performing calculations. The second one hangs an R connection in the memory so sequential calls are faster using these pre-started R process.

Here is a single pass examle. In this example, an R process is created, calculations are performed, and the process is terminated:

(defn runAndResult [code x y]
  (let [rcaller (RCaller/create)
        rcode (RCode/create)
        parser (.getParser
                (do
                  (.addRCode rcode code)
                  (.setRCode rcaller rcode)
                  (.runAndReturnResult rcaller x)
                  rcaller))
        result (.getAsDoubleArray parser y)]
    result))

Now, we send an R code and get back the results:

(runAndResult 
"
x <- rnorm(10)
m = mean(x)
s = sd(x)
result <- list(m = m, s = s)
" 
 "result" "m")

x is an random vector drawn from a standard Normal distribution. m and s are arithmetic mean and standard deviation of x, respectively. result is a list that holds these values. The runAndResult Clojure function extracts the value m from the returned list result.