add [.Pair method

git-svn-id: https://svn.r-project.org/R/trunk@88250 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: pd

doc/NEWS.Rd

@@ -102,6 +102,10 @@
 
       \item Dataset \code{LifeCycleSavings} had a misspelled row name:
       \code{"Guatamala"} was corrected to \code{"Guatemala"}.
+
+      \item The \code{Pair(x,y)} construction in the formula interface to
+      paired tests did not work with the \code{subset} argument, due to the
+      absence of a \code{[.Pair} method, which has now been added.
     }
   }
 

src/library/stats/NAMESPACE

@@ -115,6 +115,7 @@ S3method("[", formula)
 S3method("[", terms)
 S3method("[", ts)
 S3method("[", tskernel)
+S3method("[", Pair)
 S3method("[<-", ts)
 S3method("[[", dendrogram)
 S3method(add1, default)

src/library/stats/R/Pair.R

@@ -8,3 +8,16 @@ Pair <- function(x,y) {
   class(pp) <- "Pair"
   pp
 }
+`[.Pair` <- function (x, i, j, drop = FALSE) 
+{
+    if (missing(j)) {
+        x <- unclass(x)[i, , drop = FALSE]
+        class(x) <- "Pair"
+        x
+    }
+    else {
+        class(x) <- "matrix"
+        NextMethod("[")
+    }
+}
+