| axis.POSIXct {graphics} | R Documentation |
Date and Date-time Plotting Functions
Description
Add a date/time axis to the current plot of an object of class
"POSIXt" or "Date", respectively.
Usage
axis.POSIXct(side, x, at, format, labels = TRUE, ...)
axis.Date(side, x, at, format, labels = TRUE, ...)
Arguments
side |
see |
x, at |
optional date-time or Date objects, or other types of objects that can be converted appropriately. |
format |
an optional character string specifying the label format,
see |
labels |
either a logical value specifying whether
annotations are to be made at the tickmarks, or a character vector of
labels to be placed at the tick points specified by |
... |
further arguments to be passed from or to other methods, typically graphical parameters. |
Details
If at is unspecified,
axis.POSIXct and axis.Date work quite hard
(from R 4.3.0 via pretty for
date-time classes) to choose
suitable time units (years, months, days, hours, minutes, or seconds)
and a sensible label format based on the axis range.
par("lab") controls the approximate number of intervals.
If at is supplied it specifies the locations of the ticks
and labels. If the label format is unspecified, a good guess
is made by looking at the granularity of at.
Printing of tick labels can be suppressed with
labels = FALSE.
The date-times for a "POSIXct" input are interpreted in the
time zone give by the "tzone" attribute if there is one,
otherwise the current time zone.
The way the date-times are rendered (especially month names) is
controlled by the locale setting of category "LC_TIME" (see
Sys.setlocale).
Value
The locations on the axis scale at which tick marks were drawn.
See Also
DateTimeClasses, Dates for details of the classes.
Axis.
Examples
with(beaver1, {
opar <- par(mfrow = c(3,1))
time <- strptime(paste(1990, day, time %/% 100, time %% 100),
"%Y %j %H %M")
plot(time, temp, type = "l") # axis at 6-hour intervals
# request more ticks
olab <- par(lab = c(10, 10, 7))
plot(time, temp, type = "l")
par(olab)
# now label every hour on the time axis
plot(time, temp, type = "l", xaxt = "n")
r <- as.POSIXct(round(range(time), "hours"))
axis.POSIXct(1, at = seq(r[1], r[2], by = "hour"), format = "%H")
par(opar) # reset changed par settings
})
plot(.leap.seconds, seq_along(.leap.seconds), type = "n", yaxt = "n",
xlab = "leap seconds", ylab = "", bty = "n")
rug(.leap.seconds)
## or as dates
lps <- as.Date(.leap.seconds)
plot(lps, seq_along(.leap.seconds),
type = "n", yaxt = "n", xlab = "leap seconds",
ylab = "", bty = "n")
rug(lps)
## 100 random dates in a 10-week period
random.dates <- as.Date("2001/1/1") + 70*sort(stats::runif(100))
plot(random.dates, 1:100)
# or for a better axis labelling
plot(random.dates, 1:100, xaxt = "n")
axis.Date(1, at = seq(as.Date("2001/1/1"), max(random.dates)+6, "weeks"))
axis.Date(1, at = seq(as.Date("2001/1/1"), max(random.dates)+6, "days"),
labels = FALSE, tcl = -0.2)
## axis.Date() with various data types:
x <- seq(as.Date("2022-01-20"), as.Date("2023-03-21"), by = "days")
plot(data.frame(x, y = 1), xaxt = "n")
legend("topleft", title = "input",
legend = c("character", "Date", "POSIXct", "POSIXlt", "numeric"),
fill = c("violet", "red", "orange", "coral1", "darkgreen"))
axis.Date(1)
axis.Date(3, at = "2022-04-01", col.axis = "violet")
axis.Date(3, at = as.Date("2022-07-01"), col.axis = "red")
axis.Date(3, at = as.POSIXct(as.Date("2022-10-01")), col.axis = "orange")
axis.Date(3, at = as.POSIXlt(as.Date("2023-01-01")), col.axis = "coral1")
axis.Date(3, at = as.integer(as.Date("2023-04-01")), col.axis = "darkgreen")
## automatically extends the format:
axis.Date(1, at = "2022-02-15", col.axis = "violet",
col = "violet", tck = -0.05, mgp = c(3,2,0))
## axis.POSIXct() with various data types (2 minutes):
x <- as.POSIXct("2022-10-01") + c(0, 60, 120)
attributes(x) # no timezone
plot(data.frame(x, y = 1), xaxt = "n")
legend("topleft", title = "input",
legend = c("character", "Date", "POSIXct", "POSIXlt", "numeric"),
fill = c("violet", "red", "orange", "coral1", "darkgreen"))
axis.POSIXct(1)
axis.POSIXct(3, at = "2022-10-01 00:01", col.axis = "violet")
axis.POSIXct(3, at = as.Date("2022-10-01"), col.axis = "red")
axis.POSIXct(3, at = as.POSIXct("2022-10-01 00:01:30"), col.axis = "orange")
axis.POSIXct(3, at = as.POSIXlt("2022-10-01 00:02"), col.axis = "coral1")
axis.POSIXct(3, at = as.numeric(as.POSIXct("2022-10-01 00:00:30")),
col.axis = "darkgreen")
## automatically extends format (here: subseconds):
axis.POSIXct(3, at = as.numeric(as.POSIXct("2022-10-01 00:00:30")) + 0.25,
col.axis = "forestgreen", col = "darkgreen", mgp = c(3,2,0))
## axis.POSIXct: 2 time zones
HST <- as.POSIXct("2022-10-01", tz = "HST") + c(0, 60, 60*60)
CET <- HST
attr(CET, "tzone") <- "CET"
plot(data.frame(HST, y = 1), xaxt = "n", xlab = "Hawaii Standard Time (HST)")
axis.POSIXct(1, HST)
axis.POSIXct(1, HST, at = "2022-10-01 00:10", col.axis = "violet")
axis.POSIXct(3, CET)
mtext(3, text = "Central European Time (CET)", line = 3)
axis.POSIXct(3, CET, at="2022-10-01 12:10", col.axis = "violet")