diff.ts(<1x1 matrix>) now is matrix

git-svn-id: https://svn.r-project.org/R/trunk@89093 00db46b3-68df-0310-9c12-caf00c1e9a41

Author: maechler

doc/NEWS.Rd

@@ -403,6 +403,7 @@
       \item \code{diff(m, lag, dif)} for matrix \code{m} now still returns
       matrices, also when \code{lag * dif > nrow(m)} (\PR{18972}, thanks to
       \I{Mikael Jagan}).
+      \code{diff(<ts-matrix>)} remains matrix, even when it has length zero.
 
       \item \code{str(x, give.attr=FALSE)} no longer shows attributes when
       \code{x} is a zero length \code{"Date"} or \code{"POSIXt"} object.

src/library/stats/R/ts.R

@@ -243,6 +243,11 @@ Ops.ts <- function(e1, e2)
                          c(deparse(substitute(e1))[1L],
                            deparse(substitute(e2))[1L]),
                          union = FALSE)
+        if(is.null(e12))# if e1 or e2 is matrix but e1 & e2 are not overlapping, e12 is NULL ..
+            return(if(is.matrix(e1)) e1[0, , drop=FALSE]
+              else if(is.matrix(e2)) e2[0, , drop=FALSE]
+                ## else NULL ( == e12 )
+              )
         e1 <- if(is.matrix(e1)) e12[,        1L:nc1 , drop = FALSE] else e12[, 1]
         e2 <- if(is.matrix(e2)) e12[, nc1 + (1L:nc2), drop = FALSE] else e12[, nc1 + 1]
         NextMethod(.Generic)

tests/reg-tests-1e.R

@@ -2386,6 +2386,11 @@ str(L, give.attr=FALSE) # now  0 x 1  matrices
 stopifnot( print(
   vapply(L, \(.) identical(.$f0 - .$f0, .$f), NA) ) )
 ## were all FALSE : diff(fnm, 2,5) was not a matrix
+m <- ts(matrix(1)) # ts-matrix boundary case
+d1 <- m - lag(m, -1) # warning: non-intersecting series
+d2 <- diff(m)
+stopifnot(identical(d1,d2), identical(dim(d1), 0:1))
+## both d1 & d2 were *not* matrix  in R <= 4.5.2
 
 
 ## str.{Date,POSIXt}(<length 0>, give.attr=FALSE) - now works