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hist.POSIXt: Histogram of a Date or Date-Time Object

hist.POSIXt

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 = deparse1(substitute(x)),
     plot = TRUE, freq = FALSE,
     start.on.monday = TRUE, format, right = TRUE)

## S3 method for class 'Date'
hist(x, breaks, ...,
     xlab = deparse1(substitute(x)),
     plot = TRUE, freq = FALSE,
     start.on.monday = TRUE, format, right = TRUE)

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`, `density` 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`.
`right`	logical; if `TRUE`, the histogram cells are right-closed (left open) intervals.

Details

Note that unlike the default method, breaks is a required argument.

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.

With the default right = TRUE, breaks will be set on the last day of the previous period when breaks is "months", "quarters" or "years". Use right = FALSE to set them to the first day of the interval shown in each bar.

Value

An object of class "histogram": see hist.

Examples

hist(.leap.seconds, "years", freq = TRUE)
hist(.leap.seconds,
     seq(ISOdate(1970, 1, 1), ISOdate(2020, 1, 1), "5 years"))
rug(.leap.seconds, lwd=2)

## 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")