R: Pretty Breakpoints for Date-Time Classes

pretty.Date {grDevices}

R Documentation

Pretty Breakpoints for Date-Time Classes

Description

Compute a sequence of about n+1 equally spaced ‘nice’ values which cover the range of the values in x, possibly of length one, when min.n = 0 and there is only one unique x.

Usage

## S3 method for class 'Date'
pretty(x, n = 5, min.n = n %/% 2, sep = " ", ...)
## S3 method for class 'POSIXt'
pretty(x, n = 5, min.n = n %/% 2, sep = " ", ...)

Arguments

x

an object of class "Date" or "POSIXt" (i.e., "POSIXct" or "POSIXlt").

n

integer giving the desired number of intervals.

min.n

nonnegative integer giving the minimal number of intervals.

sep

character string, serving as a separator for certain formats (e.g., between month and year).

...

further arguments for compatibility with the generic, ignored.

Value

A vector (of the suitable class) of locations, with attribute "labels" giving corresponding formatted character labels and attribute "format" giving the format specification that was used.

Examples


pretty(Sys.Date())
pretty(Sys.time(), n = 10)

pretty(as.Date("2000-03-01")) # R 1.0.0 came in a leap year

## time ranges in diverse scales:
steps <- stats::setNames(,
    c("10 secs", "1 min", "5 mins", "30 mins", "6 hours", "12 hours",
      "1 DSTday", "2 weeks", "1 month", "6 months", "1 year",
      "10 years", "50 years", "1000 years"))
x <- as.POSIXct("2002-02-02 02:02")
lapply(steps,
       function(s) {
           at <- pretty(seq(x, by = s, length.out = 2), n = 5)
           attr(at, "labels")
       })