Draw a polygon on an existing xts plot by specifying a time series of y coordinates. The xts index is used for the x coordinates and the first two columns are the upper and lower y coordinates, respectively.
Arguments
- x
An xts object to plot. Must contain 2 columns for the upper and the lower y coordinates for the polygon. The first column is interpreted as upper y coordinates and the second column as the lower y coordinates.
- y
NULL, not used.- main
Main title for a new panel, if drawn.
- on
Panel number to draw on. A new panel will be drawn if
on = NA.- col
Color palette to use, set by default to rational choices.
- ...
Any other passthrough parameters to
par().
References
Based on code by Dirk Eddelbuettel from http://dirk.eddelbuettel.com/blog/2011/01/16/
Examples
if (FALSE) { # \dontrun{
library(xts)
data(sample_matrix)
x <- as.xts(sample_matrix)[,1]
ix <- index(x["2007-02"])
shade <- xts(matrix(rep(range(x), each = length(ix)), ncol = 2), ix)
plot(x)
# set on = -1 to draw the shaded region *behind* the main series
addPolygon(shade, on = -1, col = "lightgrey")
} # }