GRtime: Date time handling for the GENEAread package.

Description

Stores date time data as a numeric, with facility for pretty printing and axis commands.

Usage

as.GRtime(x, format = NULL, ...)

Arguments

x: Object to process. For convert.time, must be numeric. For as.GRtime may be numeric or character. For format.GRtime, a GRtime object, or a numeric.
format: A character string indicating the form of output. See strptime for details. If NULL, will be automatically chosen.
...: Additional arguments to be passed to parse.time, as.numeric, format.POSIXct, axis, pretty.POSIXt.

Details

The GRtime class handles dates and times for the GENEAread class. The class treats dates as numerics denoting seconds since the UNIX epoch, with potentially a string attached specifying the format to print in. Unlike POSIXct, we avoid some of the processing, especially with respect to time zones, and allow some more flexibility in time computation and display. A range of operators are defined.

convert.time converts numerics to GRtime objects. The format argument allows a format string to be attached specifying the default format to display in. as.GRtime is a wrapper to convert.time, that when supplied with character input, coerces the value first to numeric using parse.time.

format.GRtime formats GRtime objects for pretty printing. If format is provided as argument, that is used. Else, if the format attribute is set on x, that is used. Finally, if formats are not provided, and x is of length greater than one, the range of values of x is used to decide the units displayed. Numerics are also accepted - they are coerced to GRtime.

axis.GRtime is used to plot GRtime axis, choosing, by default, breakpoints that give 'pretty' sub intervals. Note that plot.default uses axis.GRtime by default if supplied with a GRtime object in one of the directions. However, image.default based functions do not use the class axis functions, so axes must be plotted manually.

pretty.GRtime computes 'pretty' breakpoints, using the algorithm of pretty.POSIXt. Attributes are preserved.

For convert.time, as.GRtime and pretty.GRtime, a GRtime object.
For format.GRtime a character string representation.
For axis.GRtime a list containing positions and labels for axis markers.

Examples

Run this code

as.GRtime("00:01")
#format is automatically set
convert.time(1:10)
convert.time(1:10*1000)
#we add a different default format
convert.time(1:10*1000, "%H:%M:%OS3") -> t
t
str(t)
# we override format with our own
format(t, format = "%a %d/%m/%y %H:%M:%OS3")

# plot calls axis.GRtime automatically. Notice
# that the format attribute is used.
plot(t, 1:10)
#strip out the default format
t2 = convert.time(t, format = NULL)
plot(t2, 1:10)

# image plots are a bit more complex

Z = matrix(rnorm(100), 10)
image(x = t, y = t2, z = Z, axes = FALSE)
Axis(x = t, side = 1) #Axis also works
box() #complete the bounding box

# custom axes
plot(t2, 1:10, xaxt = "n")

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