R: Plotting zoo Objects

plot.zoo {zoo}

R Documentation

Plotting zoo Objects

Description

Plotting method for objects of class "zoo".

Usage

## S3 method for class 'zoo':
plot(x, y = NULL, screens, plot.type,
  panel = lines, xlab = "Index", ylab = NULL, main = NULL,
  xlim = NULL, ylim = NULL, xy.labels = FALSE, xy.lines = NULL,
  oma = c(6, 0, 5, 0), mar = c(0, 5.1, 0, 2.1), 
  col = 1, lty = 1, lwd = 1, pch = 1, type = "l", nc, widths = 1, heights = 1, ...)
## S3 method for class 'zoo':
lines(x, y = NULL, type = "l", ...)
## S3 method for class 'zoo':
points(x, y = NULL, type = "p", ...)

Arguments

`x`	an object of class `"zoo"`.
`y`	an object of class `"zoo"`. If `y` is `NULL` (the default) a time series plot of `x` is produced, otherwise if both `x` and `y` are univariate `"zoo"` series, a scatter plot of `y` versus `x` is produced.
`screens`	factor (or coerced to factor) whose levels specify which graph each series is to be plotted in. `screens=c(1,2,1)` would plot series 1, 2 and 3 in graphs 1, 2 and 1. If not specified then 1 is used if `plot.type="single"` and `seq_len(ncol(x))` otherwise.
`plot.type`	for multivariate zoo objects, "multiple" plots the series on multiple plots and "single" superimposes them on a single plot. Default is "single" if `screens` has only one level and `"multiple"` otherwise. If neither `screens` nor `plot.type` is specified then `"single"` is used if there is one series and `"mulitple"` otherwise. This option is provided for back compatibility. Usually `screens` is used instead.
`panel`	a `function(x, y, col, lty, ...)` which gives the action to be carried out in each panel of the display for `plot.type = "multiple"`.
`ylim`	if `plot.type = "multiple"` then it can be a list of y axis limits. If not a list each graph has the same limits. If any list element is not a pair then its range is used instead. If `plot.type = "single"` then it is as in `plot`.
`xy.labels`	logical, indicating if `text` labels should be used in the scatter plot, or character, supplying a vector of labels to be used.
`xy.lines`	logical, indicating if `lines` should be drawn in the scatter plot. Defaults to the value of `xy.labels` if that is logical, otherwise to `FALSE`.
`xlab, ylab, main, xlim, oma, mar`	graphical arguments, see `par`.
`col, lty, lwd, pch, type`	graphical arguments that can be vectors or (named) lists. See the details for more information.
`nc`	the number of columns to use when `plot.type = "multiple"`. Defaults to `1` for up to `4` series, otherwise to `2`.
`widths, heights`	widths and heights for individual graphs, see `layout`.
`...`	additional graphical arguments.

Details

The methods for plot and lines are very similar to the corresponding ts methods. However, the handling of several graphical parameters is more flexible for multivariate series. These parameters can be vectors of the same length as the number of series plotted or are recycled if shorter. They can also be (partially) named list, e.g., list(A = c(1,2), c(3,4)) in which c(3, 4) is the default value and c(1, 2) the value only for series A. The screens argument can be specified in a similar way. If plot.type and screens conflict then multiple plots will be assumed. Also see the examples.

In the case of a custom panel the panel can reference parent.frame$panel.number in order to determine which frame the panel is being called from. See examples.

par(mfrow=...) and Axis can be used in conjunction with single panel plots in the same way as with other classic graphics.

For multi-panel graphics, plot.zoo takes over the layout so par(mfrow=...) cannot be used. Axis can be used within the panels themselves but not outside the panel. See examples.

In addition to classical time series line plots, there is also a simple barplot method for "zoo" series.

Examples

## example dates
x.Date <- as.Date(paste(2003, 02, c(1, 3, 7, 9, 14), sep = "-"))

## univariate plotting
x <- zoo(rnorm(5), x.Date)
x2 <- zoo(rnorm(5, sd = 0.2), x.Date)
plot(x)
lines(x2, col = 2)

## multivariate plotting
z <- cbind(x, x2, zoo(rnorm(5, sd = 0.5), x.Date))
plot(z, type = "b", pch = 1:3, col = 1:3, ylab = list(expression(mu), "b", "c"))
colnames(z) <- LETTERS[1:3]
plot(z, screens = 1, col = list(B = 2))
plot(z, type = "b", pch = 1:3, col = 1:3)
plot(z, type = "b", pch = list(A = 1:5, B = 3), col = list(C = 4, 2))
plot(z, type = "b", screen = c(1,2,1), col = 1:3)
# right axis is for broken lines
plot(x)
opar <- par(usr = c(par("usr")[1:2], range(x2)))
lines(x2, lty = 2)
# axis(4)
axis(side = 4)
par(opar)

## Custom x axis labelling using a custom panel.
# 1. test data
z <- zoo(c(21, 34, 33, 41, 39, 38, 37, 28, 33, 40), 
     as.Date(c("1992-01-10", "1992-01-17", "1992-01-24", "1992-01-31", 
       "1992-02-07", "1992-02-14", "1992-02-21", "1992-02-28", "1992-03-06", 
       "1992-03-13")))
zz <- merge(a = z, b = z+10)
# 2. axis tick for every point. Also every 3rd point labelled.
my.panel <- function(x, y, ..., pf = parent.frame()) {
   fmt <- "%b-%d" # format for axis labels
   lines(x, y, ...)
   # if bottom panel
   if (with(pf, length(panel.number) == 0 || 
        panel.number %% nr == 0 || panel.number == nser)) { 
      # create ticks at x values and then label every third tick
      axis(side = 1, at = x, labels = FALSE)
      ix <- seq(1, length(x), 3)
      labs <- format(x, fmt)
      axis(side = 1, at = x[ix], labels = labs[ix], tcl = -0.7, cex.axis = 0.7)
   }
}
# 3. plot
plot(zz, panel = my.panel, xaxt = "n")

# with a single panel plot a fancy x-axis is just the same
# procedure as for the ordinary plot command
plot(zz, screen = 1, col = 1:2, xaxt = "n")
# axis(1, at = time(zz), labels = FALSE)
tt <- time(zz)
axis(side = 1, at = tt, labels = FALSE)
ix <- seq(1, length(tt), 3)
fmt <- "%b-%d" # format for axis labels
labs <- format(tt, fmt)
# axis(1, at = time(zz)[ix], labels = labs[ix], tcl = -0.7, cex.axis = 0.7)
axis(side = 1, at = tt[ix], labels = labs[ix], tcl = -0.7, cex.axis = 0.7)
legend("bottomright", colnames(zz), lty = 1, col = 1:2)

## plot a mulitple ts series with nice x-axis using panel function
tab <- ts(cbind(A = 1:24, B = 24:1), start = c(2006, 1), freq = 12)
pnl.xaxis <- function(...) {
     lines(...)
     panel.number <- parent.frame()$panel.number
     nser <- parent.frame()$nser
     # if bottom panel
     if (!length(panel.number) || panel.number == nser) { 
           tt <- list(...)[[1]]
           ym <- as.yearmon(tt)
           mon <- as.numeric(format(ym, "%m"))
           yy <- format(ym, "%y")
           mm <- substring(month.abb[mon], 1, 1)
       if (any(mon == 1))
            # axis(1, tt[mon == 1], yy[mon == 1], cex.axis = 0.7)
            axis(side = 1, at = tt[mon == 1], labels = yy[mon == 1], cex.axis = 0.7)
           # axis(1, tt[mon > 1], mm[mon > 1], cex.axis = 0.5, tcl = -0.3)
           axis(side = 1, at = tt[mon > 1], labels = mm[mon > 1], cex.axis = 0.5, tcl = -0.3)
     }
}
plot(as.zoo(tab), panel = pnl.xaxis, xaxt = "n", main = "Fancy X Axis")

## Another example with a custom axis
# test data
z <- zoo(matrix(1:25, 5), c(10,11,20,21))
colnames(z) <- letters[1:5]

plot(zoo(coredata(z)), xaxt = "n", panel = function(x, y, ..., Time = time(z)) {
    lines(x, y, ...)
    # if bottom panel
    pf <- parent.frame()
    if (with(pf, panel.number %% nr == 0 || panel.number == nser)) {
        axis(side = 1, at = x, labels = Time)
    }
})

## plot with left and right axes
## modified from http://www.mayin.org/ajayshah/KB/R/html/g6.html
set.seed(1)
z <- zoo(cbind(A = cumsum(rnorm(100)), B = cumsum(rnorm(100, mean = 0.2))))
opar <- par(mai = c(.8, .8, .2, .8))
plot(z[,1], type = "l", 
  xlab = "x-axis label", ylab = colnames(z)[1])
par(new = TRUE)
plot(z[,2], type = "l", ann = FALSE, yaxt = "n", col = "blue")
# axis(4)
axis(side = 4)
legend(x = "topleft", bty = "n", lty = c(1,1), col = c("black", "blue"),
  legend = paste(colnames(z), c("(left scale)", "(right scale)")))
usr <- par("usr")
# if you don't care about srt= in text then mtext is shorter:
#   mtext(colnames(z)[2], 4, 2, col = "blue")
text(usr[2] + .1 * diff(usr[1:2]), mean(usr[3:4]), colnames(z)[2],
  srt = -90, xpd = TRUE, col = "blue")
par(opar)

# automatically placed point labels
## Not run: 
library("maptools")
pointLabel(time(z), coredata(z[,2]), labels = format(time(z)), cex = 0.5)
## End(Not run)

## plot one zoo series against the other.
plot(x, x2)
plot(x, x2, xy.labels = TRUE)
plot(x, x2, xy.labels = 1:5, xy.lines = FALSE)

## shade a portion of a plot and make axis fancier

v <- zooreg(rnorm(50), start = as.yearmon(2004), freq = 12)

plot(v, type = "n")
u <- par("usr")
rect(as.yearmon("2007-8"), u[3], as.yearmon("2009-11"), u[4], 
   border = 0, col = "grey")
lines(v)
axis(1, floor(time(v)), labels = FALSE, tcl = -1)

## shade certain times to show recessions, etc.
v <- zooreg(rnorm(50), start = as.yearmon(2004), freq = 12)
plot(v, type = "n")
u <- par("usr")
rect(as.yearmon("2007-8"), u[3], as.yearmon("2009-11"), u[4], 
   border = 0, col = "grey")
lines(v)
axis(1, floor(time(v)), labels = FALSE, tcl = -1)

## barplot
x <- zoo(cbind(rpois(5, 2), rpois(5, 3)), x.Date)
barplot(x, beside = TRUE)

## 3d plot
## The persp function in R (not part of zoo) works with zoo objects.
## The following example is by Enrico Schumann.
## https://stat.ethz.ch/pipermail/r-sig-finance/2009q1/003710.html
nC <- 10    # columns
nO <- 100 # observations
dataM <- array(runif(nC * nO), dim=c(nO, nC))
zz <- zoo(dataM, 1:nO)
persp(1:nO, 1:nC, zz)

# interactive plotting
## Not run: 
library("TeachingDemos")
tke.test1 <- list(Parameters = list(
        pch = list("spinbox", init = 1, from = 0, to = 255, width = 5),
        cex = list("slider", init = 1.5, from = 0.1, to = 5, resolution = 0.1),
        type = list("combobox", init = "b",
           values = c("p", "l", "b", "o", "c", "h", "s", "S", "n"), width = 5),
        lwd = list("spinbox", init = 1, from = 0, to = 5, increment = 1, width = 5),
        lty = list("spinbox", init = 1, from = 0, to = 6, increment = 1, width = 5)
))
z <- zoo(rnorm(25))
tkexamp(plot(z), tke.test1, plotloc = "top")
## End(Not run)