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.

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.

See Also

pretty for the default method.

Examples

steps <-
    list("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")

names(steps) <- paste("span =", unlist(steps))

x <- as.POSIXct("2002-02-02 02:02")
lapply(steps,
       function(s) {
           at <- pretty(seq(x, by = s, length = 2), n = 5)
           attr(at, "labels")
       })

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