tinyplot method for 'ts' time series objects

NAMESPACE

@@ -3,6 +3,7 @@
 S3method(tinyplot,default)
 S3method(tinyplot,density)
 S3method(tinyplot,formula)
+S3method(tinyplot,ts)
 export(draw_legend)
 export(get_saved_par)
 export(plt)
@@ -122,6 +123,7 @@ importFrom(stats,quantile)
 importFrom(stats,setNames)
 importFrom(stats,spline)
 importFrom(stats,terms)
+importFrom(stats,time)
 importFrom(stats,weighted.mean)
 importFrom(tools,file_ext)
 importFrom(utils,globalVariables)

NEWS.md

@@ -6,6 +6,13 @@ where the formatting is also better._
 
 ## Development version
 
+### New features
+
+- New dedicated `tinyplot()` method for `ts` time series. Internally, this sets
+  up a long data frame with columns `Time`, `Value`, and `Series` and then calls
+  the formula method with different possible specifications for the `by` and `facet`
+  variables. (#558 @zeileis)
+
 ### Aesthetic changes
 
 - The legend plot characters for the `"pointrange"` and `"errorbar"` types now

R/tinyplot.ts.R

@@ -0,0 +1,70 @@
+#' tinyplot Method for Plotting ts Objects (Time Series)
+#'
+#' @description Convenience interface for visualizing ts objects
+#'   (time sereis with tinyplot.
+#'
+#' @details Internally the time series object is converted to a long
+#'   data frame with columns `Time` (time index), `Value` (observations),
+#'   and `Series` (factor with column labels). Depending on the settings
+#'  of `facet` this data frame is visualized either with the formula
+#'  `Value ~ Time` or `Value ~ Time | Series`. See the `facet` argument
+#'  description for more details and the examples for some illustrations.
+#'
+#' @param x an object of class `"ts"`.
+#' @param facet specification of `facet` for `tinyplot.formula`. The
+#'   default in the `tinyplot` method is to use `facet = NULL` for univariate
+#'   series and `facet = ~ Series` (equivalent to `facet = "by"`) for multivariate series.
+#' @param type,facet.args,ylab,... further arguments passed to `tinyplot`. 
+#'
+#' @examples
+#' tinytheme("clean2")
+#' 
+#' ## univariate series
+#' tinyplot(Nile)
+#' 
+#' ## multivariate 
+#' tinyplot(EuStockMarkets)                    ## multiple, same color, free scales
+#' tinyplot(EuStockMarkets, facet.args = NULL) ## multiple, same color, same scale
+#' tinyplot(EuStockMarkets, facet = "by")      ## multiple, separate colors, free scales
+#' tinyplot(EuStockMarkets, facet = NULL)      ## single, separate colors
+#'
+#' ## further variations
+#' tinyplot(EuStockMarkets, facet = "by", facet.args = NULL)
+#' tinyplot(EuStockMarkets, facet.args = list(free = TRUE, ncol = 1))
+#'
+#' tinytheme() ## reset
+#'
+#' @importFrom stats time
+#' @export
+tinyplot.ts = function(x, facet, type = "l", facet.args = list(free = TRUE), ylab = "", ...) {
+  ## basic object properties
+  n = NROW(x)
+  k = NCOL(x)
+  lab = deparse(substitute(x))
+  if (k > 1L) lab = paste(lab, 1L:k, sep = ".")
+  if (!is.null(colnames(x))) lab = colnames(x)
+
+  ## convert to long data.frame
+  df = data.frame(
+    Time = rep.int(as.numeric(time(x)), k),
+    Value = as.numeric(x),
+    Series = factor(rep(1L:k, each = n), labels = lab)
+  )
+
+  ## default for facet
+  single = k == 1L
+  if(missing(facet)) {
+    auto = TRUE
+    facet = if(single) NULL else ~ Series
+  } else {
+    auto = FALSE
+  }
+  if (is.null(facet)) facet.args = NULL
+
+  ## call tinyplot
+  if(single | (!is.null(facet) & auto)) {
+    tinyplot(Value ~ Time, data = df, facet = facet, facet.args = facet.args, type = type, ylab = ylab, ...)
+  } else {
+    tinyplot(Value ~ Time | Series, data = df, facet = facet, facet.args = facet.args, type = type, ylab = ylab, ...)
+  }
+}