R, and the many incredibly useful packages that have been developed for it, provides a rich environment to do statistical computing. To access any of this, however, we'll need to be able to call functions from Clojure. We do this by constructing R expressions as strings, sending them to the R server, and getting the results back. The Rserve Java library helps us convert the results to Java objects that we can access.
We must first complete the recipe, Setting up R to talk to Clojure, and have Rserve running. We must also have the Clojure-specific parts of that recipe done and the connection to Rserve made.
Once we have a connection to Rserver, we can call functions by passing the complete call—function and arguments—to the server as a string and evaluating it. Then, we have to pull the results back out, as follows:
user=> (map #(.asDouble %)
(.. *r-cxn* (eval "qr(c(1,2,3,4,5,6,7))") asList))
(-11.832159566199232 1.0 1...