fix PR#15068 and more

git-svn-id: https://svn.r-project.org/R/trunk@60904 00db46b3-68df-0310-9c12-caf00c1e9a41
wch · Oct 8, 2012 · eda9c0e · eda9c0e
1 parent 95db153
commit eda9c0e
Show file tree

Hide file tree

Showing 4 changed files with 20 additions and 5 deletions.
diff --git a/doc/NEWS.Rd b/doc/NEWS.Rd
@@ -980,6 +980,9 @@
       \item The code for creating \code{coerce()} methods could
       generate false notes about ambiguous selection; the notes have
       been suppressed for this function.
+
+      \item \code{arima.sim()} could give too long an output in some
+      corner cases (in part, \PR{15068}).
     }
   }
 }

diff --git a/src/library/stats/R/ts.R b/src/library/stats/R/ts.R
@@ -765,6 +765,7 @@ arima.sim <- function(model, n, rand.gen = rnorm,
                       start.innov = rand.gen(n.start, ...), ...)
 {
     if(!is.list(model)) stop("'model' must be list")
+    if(n <= 0L) stop("'n' must be strictly positive")
     p <- length(model$ar)
     if(p) {
         minroots <- min(Mod(polyroot(c(1, -model$ar))))
@@ -788,13 +789,13 @@ arima.sim <- function(model, n, rand.gen = rnorm,
                               "'start.innov' is too short: need %d point",
                               "'start.innov' is too short: need %d points"),
                      n.start), domain = NA)
-    x <- ts(c(start.innov[1L:n.start], innov[1L:n]), start = 1 - n.start)
+    x <- ts(c(start.innov[seq_len(n.start)], innov[1L:n]), start = 1 - n.start)
     if(length(model$ma)) {
         x <- filter(x, c(1, model$ma), sides = 1L)
         x[seq_along(model$ma)] <- 0 # rather than NA
     }
     if(length(model$ar)) x <- filter(x, model$ar, method = "recursive")
-    if(n.start > 0) x <- x[-(1L:n.start)]
+    if(n.start > 0) x <- x[-(seq_len(n.start))]
     if(d > 0) x <- diffinv(x, differences = d)
     as.ts(x)
 }
diff --git a/src/library/stats/man/arima.sim.Rd b/src/library/stats/man/arima.sim.Rd
@@ -1,6 +1,6 @@
 % File src/library/stats/man/arima.sim.Rd
 % Part of the R package, http://www.R-project.org
-% Copyright 1995-2007 R Core Team
+% Copyright 1995-2012 R Core Team
 % Distributed under GPL 2 or later
 
 \name{arima.sim}
@@ -18,9 +18,10 @@ arima.sim(model, n, rand.gen = rnorm, innov = rand.gen(n, \dots),
 \arguments{
   \item{model}{A list with component \code{ar} and/or \code{ma} giving
     the AR and MA coefficients respectively.  Optionally a component
-    \code{order} can be used. An empty list gives an ARIMA(0, 0, 0)
+    \code{order} can be used.  An empty list gives an ARIMA(0, 0, 0)
     model, that is white noise.}
-  \item{n}{length of output series, before un-differencing.}
+  \item{n}{length of output series, before un-differencing.  A stricly
+    positive integer.}
   \item{rand.gen}{optional: a function to generate the innovations.}
   \item{innov}{an optional times series of innovations.  If not
     provided, \code{rand.gen} is used.}

diff --git a/tests/reg-tests-1b.R b/tests/reg-tests-1b.R
@@ -1979,8 +1979,18 @@ if(is.na(z[2]) || is.na(z10[2])) {
 } else stopifnot(z[2] > z10[2])
 ## Previous test ould be defeated by compiler optimization.
 
+
+##
 options(max.print=.Machine$integer.max)
 1 ## segfaulted because of integer overflow
 stopifnot(identical(.Machine$integer.max, getOption("max.print")))
+##
+
+## corner cases for arima.sim(), in part PR#15068
+stopifnot(length(arima.sim(list(order = c(0,0,0)), n = 10)) == 10)
+stopifnot(inherits(try(arima.sim(list(order = c(1,0,0), ar = 0.7), n = 0)),
+                   "try-error"))
+## one too long in R < 2.15.2
+
 
 proc.time()