R: Convert a Date or Date-Time Object to a Factor

cut.POSIXt {base} | R Documentation

## Convert a Date or Date-Time Object to a Factor

### Description

Method for `cut` applied to date-time objects.

### Usage

    ## S3 method for class 'POSIXt'
    cut(x, breaks, labels = NULL, start.on.monday = TRUE,
        right = FALSE, ...)

    ## S3 method for class 'Date'
    cut(x, breaks, labels = NULL, start.on.monday = TRUE,
        right = FALSE, ...)

### 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 `"sec"`, `"min"`, `"hour"`, `"day"`, `"DSTday"`, `"week"`, `"month"`, `"quarter"` or `"year"`, optionally preceded by an integer and a space, or followed by `"s"`. (For `"Date"` objects only interval specifications using `"day"`, `"week"`, `"month"`, `"quarter"` and `"year"` are allowed.)
`labels` | labels for the levels of the resulting category. By default, labels are constructed from the left-hand end of the intervals (which are included for the default value of `right`). If `labels = FALSE`, simple integer codes are returned instead of a factor.
`start.on.monday` | logical. If `breaks = "weeks"`, should the week start on Mondays or Sundays?
`right, ...` | arguments to be passed to or from other methods.

### Details

Note that the default for `right` differs from the default method. Using `include.lowest = TRUE` will include both ends of the range of dates.

Using `breaks = "quarter"` 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.

A vector of `breaks` will be sorted before use: `labels` should correspond to the sorted vector.

### Value

A factor is returned, unless `labels = FALSE` which returns the integer level codes.

Values which fall outside the range of `breaks` are coded as `NA`, as are and `NA` values.

### See Also

`seq.POSIXt`, `seq.Date`, `cut`

### Examples

    ## random dates in a 10-week period
    cut(ISOdate(2001, 1, 1) + 70*86400*stats::runif(100), "weeks")
    cut(as.Date("2001/1/1") + 70*stats::runif(100), "weeks")

    # The standards all have midnight as the start of the day, but some
    # people incorrectly interpret it at the end of the previous day ...
    tm <- seq(as.POSIXct("2012-06-01 06:00"), by = "6 hours", length.out = 24)
    aggregate(1:24, list(day = cut(tm, "days")), mean)
    # and a version with midnight included in the previous day:
    aggregate(1:24, list(day = cut(tm, "days", right = TRUE)), mean)

[Package base version 3.1.2 Index]