[R] Plotting on log scale using plot.date()

[Uwe Ligges]

Roger Peng wrote:
> 
> Hi, I'm trying to use the date library and I think I'm getting an
> incorrect warning when I make a plot with plot.date().  For example:
> 
> > library(date)
> > x <- as.date(1:100)
> > y <- 1:100
> > plot(x, y, log = "y")
> Warning message:
> parameter "log" couldn't be set in high-level plot() function

It is a warning message, not an error message.
In this particular case the warning message can be ignored, because the
resulting plot is exactly looking as expected.


> The problem appears to be in the last line of plot.date() function where
> the x-axis is being created.  There is a call to axis() and the log = "y"
> parameter is being passed.
> 
> I noticed a similar-sounding bug in the bugs repository (#1235) but I
> don't think it's related.
> 
> Here's the code for plot.date().  I think problem is at the end.
> 
> plot.date
> function (x, y, ..., axes, xaxt, xlab, ylab, xlim = range(x,
>     na.rm = TRUE), ylim = range(y, na.rm = TRUE))
> {
>     [ ... some code ... ]
>     else {
>         plot(x, y, ..., xaxt = "n", xlab = xlab, ylab = ylab,
>             xlim = xlim, ylim = ylim)
>         x <- c(x[!is.na(x)], xlim)
>         xd <- date.mdy(x)
>         temp <- pretty(x, n = par("lab")[1])
>         delta <- temp[2] - temp[1]
>         if (delta < 1)
>             temp <- seq(min(x), max(x), 1)
>         else if (delta > 182) {
>             temp <- xd$year + (x - mdy.date(1, 1, xd$year))/365
>             temp <- pretty(temp, n = par("lab")[1])
>             temp <- mdy.date(1, 1, floor(temp)) + floor((temp%%1) *
>                 365)
>         }
>         axis(1, temp, as.character.date(temp), ...)
>     }
> }
> 
> Should ... be passed to axis?

Yes, it should. One example that it is useful: 
  plot(x, y, log = "y", cex.axis=2)


Uwe Ligges
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