A specialized variant of
axis.POSIXct() that produces
results with less ambiguity in axis labels.
oce.axis.POSIXct( side, x, at, tformat, labels = TRUE, drawTimeRange, abbreviateTimeRange = FALSE, drawFrequency = FALSE, cex.axis = par("cex.axis"), cex.lab = par("cex.lab"), cex.main = par("cex.main"), mar = par("mar"), mgp = par("mgp"), main = "", debug = getOption("oceDebug"), ... )
Optional indication of whether/how to draw the time range
in the margin on the side of the the plot opposite the time axis. If this is
not supplied, it defaults to the value returned by
|cex.axis, cex.lab, cex.main||
character expansion factors for axis numbers, axis names and plot titles; see
title of plot
a flag that turns on debugging. Set to 1 to get a moderate amount of debugging information, or to 2 to get more.
A vector of times corresponding to axis ticks is returned silently.
The tick marks are set automatically based on examination of the time range on the axis. The scheme was devised by constructing test cases with a typical plot size and font size, and over a wide range of time scales. In some categories, both small tick marks are interspersed between large ones.
The user may set the format of axis numbers with the
If this is not supplied, the format is set based on the time span of the axis:
If this time span is less than a minute, the time axis labels are in
seconds (fractional seconds, if the interval is less than 2 seconds), with
leading zeros on small integers. (Fractional seconds are enabled with a trick:
the usual R format
"\%S" is supplemented with a new format e.g.
"\%.2S", meaning to use two digits after the decimal.)
If the time span exceeds a minute but is less than 1.5 days, the label
If the time span exceeds 1.5 days but is less than 1 year, the format is
"\%b \%d" (e.g. Jul 15) and, again, the tick marks are set up for several
If the time span exceeds a year, the format is
"\%Y", i.e. the year
is displayed with 4 digits.
It should be noted that this scheme differs from the R approach in several ways. First, R writes day names for some time ranges, in a convention that is seldom seen in the literature. Second, R will write nn:mm for both HH:MM and MM:SS, an ambiguity that might confuse readers. Third, the use of both large and small tick marks is not something that R does.
Bear in mind that
tformat may be set to alter the number format, but
that the tick mark scheme cannot (presently) be controlled.
This is used mainly by