hist.POSIXt             package:graphics             R Documentation

Histogram of a Date or Date-Time Object

Description:

     Method for 'hist' applied to date or date-time objects.

Usage:

     ## S3 method for class 'POSIXt':
     hist(x, breaks, ...,
          xlab = deparse(substitute(x)),
          plot = TRUE, freq = FALSE,
          start.on.monday = TRUE, format)

     ## S3 method for class 'Date':
     hist(x, breaks, ...,
          xlab = deparse(substitute(x)),
          plot = TRUE, freq = FALSE,
          start.on.monday = TRUE, format)

Arguments:

       x: an object inheriting from class '"POSIXt"' or '"Date"'.

  breaks: a vector of cut points _or_ number giving the number of
          intervals which 'x' is to be cut into _or_ an interval
          specification, one of '"days"', '"weeks"', '"months"',
          '"quarters"' or '"years"', plus '"secs"', '"mins"', '"hours"'
          for date-time objects. 

     ...: graphical parameters, or arguments to 'hist.default' such as
          'include.lowest', 'right' and 'labels'.

    xlab: a character string giving the label for the x axis, if
          plotted.

    plot: logical.  If 'TRUE' (default), a histogram is plotted,
          otherwise a list of breaks and counts is returned.

    freq: logical; if 'TRUE', the histogram graphic is a representation
          of frequencies, i.e, the 'counts' component of the result; if
          'FALSE', _relative_ frequencies (probabilities) are plotted.

start.on.monday: logical. If 'breaks = "weeks"', should the week start
          on Mondays or Sundays?

  format: for the x-axis labels. See 'strptime'.

Details:

     Using 'breaks = "quarters"' will create intervals of 3 calendar
     months, with the intervals beginning on January 1, April 1, July 1
     or October 1, based upon 'min(x)' as appropriate.

Value:

     An object of class '"histogram"': see 'hist'.

See Also:

     'seq.POSIXt', 'axis.POSIXct', 'hist'

Examples:

     hist(.leap.seconds, "years", freq = TRUE)
     hist(.leap.seconds,
          seq(ISOdate(1970, 1, 1), ISOdate(2010, 1, 1), "5 years"))

     ## 100 random dates in a 10-week period
     random.dates <- as.Date("2001/1/1") + 70*stats::runif(100)
     hist(random.dates, "weeks", format = "%d %b")

