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<html><head><title>R: Plot many time series in parallel</title>


</head><body>

<table width="100%" summary="page for horizonplot {latticeExtra}"><tr><td>horizonplot {latticeExtra}</td><td align="right">R Documentation</td></tr></table>

<h2>Plot many time series in parallel</h2>


<h3>Description</h3>

<p>
Plot many time series in parallel by cutting the y range into segments
and overplotting them with color representing the magnitude and
direction of deviation.
</p>


<h3>Usage</h3>

<pre>
horizonplot(x, data, ...)

## Default S3 method:
horizonplot(x, data = NULL, ...,
            panel = panel.horizonplot,
            prepanel = prepanel.horizonplot,
            strip = FALSE, strip.left = TRUE,
            par.strip.text = list(cex = 0.6),
            groups = NULL,
            default.scales =
              list(y = list(relation = "sliced", axs = "i", 
                            draw = FALSE, tick.number = 2)))

panel.horizonplot(x, y, ..., origin,
            border = NA, col.regions = regions$col)

prepanel.horizonplot(x, y, ..., origin = function(y) na.omit(y)[1])
</pre>


<h3>Arguments</h3>

<table summary="R argblock">
<tr valign="top"><td><code>x, y</code></td>
<td>
 Argument on which argument dispatch is carried
out. Typically this will be a multivariate time series.
</p>
<p>
In the panel and prepanel functions, these are the data
coordinates. 
</td></tr>
<tr valign="top"><td><code>data</code></td>
<td>
 Not used (at least, not used by <code>xyplot.ts</code>). </td></tr>
<tr valign="top"><td><code>...</code></td>
<td>

further arguments.  Arguments to <code>xyplot</code> as
well as to the default panel function <code><a href="#horizonplot">panel.horizonplot</a></code>
can be supplied directly to <code>horizonplot</code>.
</p>
<p>
In typical usage, the method of <code>xyplot</code> called will be
<code>xyplot.ts</code>.
</td></tr>
<tr valign="top"><td><code>panel</code></td>
<td>
 function to render the graphic given the data.  This is
the function that actually implements the display.  </td></tr>
<tr valign="top"><td><code>prepanel</code></td>
<td>
 function determining range of the data rectangle from
data to be used in a panel. </td></tr>
<tr valign="top"><td><code>strip, strip.left</code></td>
<td>

by default strips are only drawn on the left, to save space.
</td></tr>
<tr valign="top"><td><code>par.strip.text</code></td>
<td>

graphical parameters for the strip text; see
<code>xyplot</code>. One notable argument here is
<code>lines</code>, allowing multi-line text.
</td></tr>
<tr valign="top"><td><code>default.scales</code></td>
<td>
 
see <code>xyplot</code>.
</td></tr>
<tr valign="top"><td><code>groups</code></td>
<td>

not applicable to this type of plot.
</td></tr>
<tr valign="top"><td><code>origin</code></td>
<td>

the baseline y value for the first (positive) segment. This can be a
number, which is then fixed across all panels, or it can be a
function, which is evaluated with the <code>y</code> values in each
panel. The default is the first non-missing y value in each
panel.
</p>
<p>
See the Details section.
</td></tr>
<tr valign="top"><td><code>border</code></td>
<td>

border color for the filled polygons, defaults to no border.
</td></tr>
<tr valign="top"><td><code>col.regions</code></td>
<td>

color scale, taken by default from the current theme,
<code>trellis.par.get("regions")$col</code>. This should be a divergent
color scale (with white as the central color).
</td></tr>
</table>


<h3>Details</h3>

<p>
This function draws time series as filled areas, with modifications
to effectively visualise many time series in parallel. Data that would
be drawn off the top of each panel is redrawn from the bottom of the
panel in a darker color. Values below the origin are inverted and
drawn in the opposite color. There are up to three shades (typically
in blue) for data above the baseline and up to three shades (typically
in red) for data below the baseline. See the article referenced below
for an introduction to Horizon plots.
</p>
<p>
Note that the y scale in each panel defines the actual origin and
scale used. The <code>origin</code> argument is only used in the <code>prepanel</code>
function to choose an appropriate y scale (it is ignored by the
<code>panel</code> function). The <code>ylim</code> argument therefore over-rides
<code>origin</code>. The choice of <code>scales$y$relation</code> is also crucial;
see <code>xyplot</code> and the examples below.
</p>


<h3>Value</h3>

<p>
An object of class <code>"trellis"</code>. The
<code>update</code> method can be used to
update components of the object and the
<code>print</code> method (usually called by
default) will plot it on an appropriate plotting device.
</p>


<h3>Author(s)</h3>

<p>
Felix Andrews <a href="mailto:felix@nfrac.org">felix@nfrac.org</a>
</p>


<h3>References</h3>

<p>
Stephen Few (2008). Time on the Horizon.
<EM>Visual Business Intelligence Newsletter</EM>, June/July 2008
<a href="http://www.perceptualedge.com/articles/visual_business_intelligence/time_on_the_horizon.pdf">http://www.perceptualedge.com/articles/visual_business_intelligence/time_on_the_horizon.pdf</a>
</p>


<h3>See Also</h3>

<p>
<code>Lattice</code>,
<code>xyplot.ts</code>,
<code><a href="#panel.xyarea">panel.xyarea</a></code>
</p>


<h3>Examples</h3>

<pre>
## generate a random time series object with 12 columns
set.seed(1)
dat &lt;- ts(matrix(cumsum(rnorm(200 * 12)), ncol = 12))
colnames(dat) &lt;- paste("series", LETTERS[1:12])

## show simple line plot first, for reference.
xyplot(dat, scales = list(y = "same"))

## horizonplot:
## draw each series with a different baseline;
## ('origin' default is the first data value in each series).
## This highlights deviations within each series.
horizonplot(dat, layout = c(1,12))

## now use same scales in each panel
## (so colors represent common ranges across all panels).
## This highlights differences across series.
## One could potentially draw a colorkey in this case.
horizonplot(dat, scales = list(y = list(relation = "same")),
            origin = 0, layout = c(1,12)) +
  layer(panel.scaleArrow(x = .99, pos = 2))

## illustration of the cut points used in the following plot
xyplot(EuStockMarkets, scales = list(y = "same"),
  panel = function(x, y, ...) {
    rgn &lt;- trellis.par.get("regions")$col
    col &lt;- rgn[1 + (length(rgn)-1) * 0:7/7]
    for (i in c(-4:-1, 3:0)) {
      if (i &gt;= 0)
        yi &lt;- pmax(4000, pmin(y, 4000 + 1000 * (i+1)))
      if (i &lt; 0)
        yi &lt;- pmin(4000, pmax(y, 4000 + 1000 * i))
      panel.xyarea(x, yi, origin = 4000,
        col = col[i+5], border = NA)
    }
    panel.lines(x, y)
    panel.abline(h = 4000, lty = 2)
  })

## compare with previous plot
horizonplot(EuStockMarkets, strip.left = TRUE,
  scales = list(y = list(relation = "same")), ylim = c(4000, 5000)) +
layer(panel.scaleArrow(x = 0.99, col = "grey", srt = 90, cex = 0.75))

## a cut-and-stack plot; should use "same" y scales!
horizonplot(sunspots, cut = list(n = 23, overlap = 0),
  scales = list(y = list(relation = "same"), draw = FALSE),
  origin = 100, strip.left = FALSE, layout = c(1,23)) +
layer(grid::grid.text(round(x[1]), x = 0, just = "left"))
</pre>

<div align="center">[Package <em>latticeExtra</em> version 0.6-12 <a href="00Index.html">Index</a>]</div>
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