Full_Name: Gavin Simpson
Version: 2.1.0-patched (1-Jun-2005)
OS: Linux (Fedora Core 3)
Submission from: (NULL) (128.40.32.76)
axis.Date() insists on labelling tick marks. It could be made more flexible by
allowing the user to specify if they want the ticks to be labelled, for example,
to add un-labelled minor ticks for "months", added to a plot with "years"
labelled. The user can not define labels = "" in the "..." in the call to
axis.Date() as axis.Date() calls axis() with labels = labels explicitly,
resulting in:
Error in axis(side, at = z, labels = labels, ...) :
formal argument "labels" matched by multiple actual arguments
if you try.
One way round this would be to add labels as a named argument to axis.Date() and
to allow labels to be NULL (missing), TRUE or FALSE. A first attempt at this is
shown below:
axis.Date2 <- function (side, x, at, format, labels, ...)
{
mat <- missing(at)
if (!mat)
x <- as.Date(at)
else x <- as.Date(x)
range <- par("usr")[if (side%%2)
1:2
else 3:4]
range[1] <- ceiling(range[1])
range[2] <- floor(range[2])
d <- range[2] - range[1]
z <- c(range, x[is.finite(x)])
class(z) <- "Date"
if (d < 7)
if (missing(format))
format <- "%a"
if (d < 100) {
z <- structure(pretty(z), class = "Date")
if (missing(format))
format <- "%b %d"
}
else if (d < 1.1 * 365) {
zz <- as.POSIXlt(z)
zz$mday <- 1
zz$mon <- pretty(zz$mon)
m <- length(zz$mon)
m <- rep.int(zz$year[1], m)
zz$year <- c(m, m + 1)
z <- .Internal(POSIXlt2Date(zz))
if (missing(format))
format <- "%b"
}
else {
zz <- as.POSIXlt(z)
zz$mday <- 1
zz$mon <- 0
zz$year <- pretty(zz$year)
z <- .Internal(POSIXlt2Date(zz))
if (missing(format))
format <- "%Y"
}
if (!mat)
z <- x[is.finite(x)]
z <- z[z >= range[1] & z <= range[2]]
z <- sort(unique(z))
# if labels is missing or TRUE generate labels for ticks
if (missing(labels) || labels == TRUE)
labels <- format.Date(z, format = format)
# else rep "" to suppress labelling
else labels <- rep("", length(z))
axis(side, at = z, labels = labels, ...)
}
An example of using this with the Date example from ?plot.Date :
random.dates <- as.Date("2001/1/1") + 70*sort(runif(100))
plot(random.dates, 1:100, xaxt="n")
axis.Date2(1, at=seq(as.Date("2001/1/1"), max(random.dates)+6, "weeks"))
axis.Date2(1, at=seq(as.Date("2001/1/1"), max(random.dates)+6, "days"),
labels = FALSE, tcl = -0.2)
The function should perhaps enforce NULL/TRUE/FALSE for labels, or could be
enhanced to allow labels = "" explicitly or to allow user defined vector for
labels that is of length(at).
Thanks,
Gavin
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