Added head.ts() and tail.ts()

ChangeLog

@@ -1,5 +1,6 @@
 Version 7.4 (?? 2016)
   * Added gghistogram() and checkresiduals()
+  * Added head.ts() and tail.ts(), so head and tail now work properly on ts objects.
   * Bug fixes
 
 Version 7.3 (12 October 2016)

NAMESPACE

@@ -20,10 +20,9 @@ importFrom("stats", "Box.test", "acf", "approx", "ar", "arima",
              "qnorm", "qt", "quantile", "residuals", "rnorm", "runif",
              "sd", "simulate", "smooth.spline", "start", "stl", "supsmu",
              "terms", "time", "ts", "tsp", "tsp<-", "tsdiag", "var")
-importFrom("utils", "packageVersion", "tail")
+importFrom("utils", "packageVersion", "tail", "head")
 importFrom("ggplot2","autoplot","fortify")
 importFrom("stats", "aggregate", "as.formula", "is.mts", "reformulate")
-importFrom("utils", "head")
 
 export(arfima, Arima, arima.errors, arimaorder, auto.arima, BoxCox, croston,
 fitted.Arima, forecast, forecast.ar, forecast.Arima, forecast.ets, forecast.fracdiff,findfrequency,
@@ -87,6 +86,8 @@ S3method(getResponse,Arima)
 S3method(getResponse,default)
 S3method(getResponse,fracdiff)
 S3method(getResponse,lm)
+S3method(head,ts)
+S3method(tail,ts)
 S3method(logLik,ets)
 S3method(plot,ar)
 S3method(plot,Arima)

R/subset.R

@@ -48,7 +48,7 @@ subset.ts <- function(x, subset=NULL, month=NULL, quarter=NULL, season=NULL, ...
   else
     if(min(season) < 1L | max(season) > frequency(x))
       stop(paste("Seasons must be between 1 and", frequency(x)))
-  
+
   start <- utils::head(time(x)[is.element(cycle(x), season)],1)
   if("mts" %in% class(x)){
     x <- subset.matrix(x, is.element(cycle(x), season))
@@ -58,3 +58,28 @@ subset.ts <- function(x, subset=NULL, month=NULL, quarter=NULL, season=NULL, ...
   }
     return(ts(x, frequency=length(season), start=start))
 }
+
+head.ts <- function(x, n=6L, ...)
+{
+  tspx <- tsp(x)
+  if(NCOL(x) > 1)
+    hx <- ts(utils::head.matrix(as.matrix(x), n=n, ...),
+      start=tspx[1], frequency=tspx[3])
+  else
+    hx <- ts(head(c(x), n=n, ...),
+             start=tspx[1], frequency=tspx[3])
+  return(hx)
+}
+
+
+tail.ts <- function(x, n=6L, ...)
+{
+  tspx <- tsp(x)
+  if(NCOL(x) > 1)
+    hx <- ts(utils::tail.matrix(as.matrix(x), n=n, ...),
+             end=tspx[2], frequency=tspx[3])
+  else
+    hx <- ts(tail(c(x), n=n, ...),
+             end=tspx[2], frequency=tspx[3])
+  return(hx)
+}