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ylab in plot.POSIXct

2 messages · Ed Kademan, Dirk Eddelbuettel

Ed Kademan
# 
I am using R-1.7.0 and have some data which consist of one vector of
numbers and a second corresponding vector of dates belonging to the
POSIXct class.  I would like to plot the numbers against the dates.
What is the best way to do this?

It almost works to just call `plot.'  However if I do this while using
the `ylab' parameter I get a warning message:

  parameter "ylab" couldn't be set in high-level plot() function 

Here is a function that demonstrates the behavior.

  ylabProblem <- function() {
    x <- ISOdate(2003, 4, 1:10)           # POSIXct vector
    y <- rnorm(10)
    plot(x, y, ylab = 'I am y')
  }

It works to invoke the low-level plotting routines by hand as follows:

  ylabNoProblem <- function() {
    x <- ISOdate(2003, 4, 1:10)           # POSIXct vector
    y <- rnorm(10)
    plot.default(x, y, xaxt = 'n', xlab = '', ylab = 'I am y')
    axis.POSIXct(1, x)
  }

But I don't like calling methods explicitly like this.
Dirk Eddelbuettel
#
On Wed, Apr 30, 2003 at 03:10:52PM -0400, Ed Kademan wrote:
ylabThisWorks <- function() {
   x <- ISOdate(2003, 4, 1:10)           # POSIXct vector
   y <- rnorm(10)
   plot(x,y, ann=FALSE)     # use ann=F, not axes=F
   title(ylab="I am y")     # and add the desired label
}   

Hth, Dirk