gnu: Add r-extremes.

* gnu/packages/cran.scm (r-extremes): New variable.

gnu/packages/cran.scm

@@ -638,3 +638,28 @@ interval calculation and to distill pertinent information from a potentially
 complex object; primarily used in common with the packages extRemes and
 SpatialVx.")
     (license license:gpl2+)))
+
+(define-public r-extremes
+  (package
+    (name "r-extremes")
+    (version "2.0-8")
+    (source
+     (origin
+       (method url-fetch)
+       (uri (cran-uri "extRemes" version))
+       (sha256
+        (base32
+         "0pnpib3g2r9x8hfqhvq23j8m3jh62lp28ipnqir5yadnzv850gfm"))))
+    (properties `((upstream-name . "extRemes")))
+    (build-system r-build-system)
+    (propagated-inputs
+     `(("r-car" ,r-car)
+       ("r-distillery" ,r-distillery)
+       ("r-lmoments" ,r-lmoments)))
+    (home-page "http://www.assessment.ucar.edu/toolkit/")
+    (synopsis "Extreme value analysis")
+    (description
+     "ExtRemes is a suite of functions for carrying out analyses on the
+extreme values of a process of interest; be they block maxima over long blocks
+or excesses over a high threshold.")
+    (license license:gpl2+)))