Ops.Date
Ops Group Method for Date/Time Objects

### Description

The group method defining mathematical operations on date/time objects.

### Usage

    ## Date
    Date Compare Date   -> logical
    + Date              -> Date
    Date - Date         -> difftime
    Date + numeric      -> Date
    Date - numeric      -> Date
    Date + difftime     -> Date
    Date - difftime     -> Date
    numeric + Date      -> Date
    difftime + Date     -> Date
    ## POSIXt
    POSIXt Compare POSIXt   -> logical
    + POSIXt                -> POSIXt
    POSIXt - POSIXt         -> difftime
    POSIXt + numeric        -> POSIXt
    POSIXt - numeric        -> POSIXt
    POSIXt + difftime       -> POSIXt
    POSIXt - difftime       -> POSIXt
    numeric + POSIXt        -> POSIXt
    difftime + POSIXt       -> POSIXt
    ## difftime
    difftime Compare difftime   -> logical
    + difftime                  -> difftime
    - difftime                  -> difftime
    difftime + difftime         -> difftime
    difftime - difftime         -> difftime
    difftime + numeric          -> difftime
    difftime - numeric          -> difftime
    numeric + difftime          -> difftime
    numeric - difftime          -> difftime
    difftime * numeric          -> difftime
    difftime / numeric          -> difftime
    numeric * difftime          -> difftime

### Arguments

Date | a Date object.
POSIXt | a POSIXt object.
difftime | a difftime object.
numeric | a numeric object.
logical | a logical object.
Compare | a logic operator including "<", ">", "!=", "==", "<=" and ">=".

### Details

- For operations involving both Date and numeric, the numeric is treated as the number of days.
- For operations involving both POSIXt and numeric, the numeric is treated as the number of seconds.
- For operations involving both difftime and numeric, the numeric is treated as the number of units of the difftime object.

Value
an object as described in the usage section.
See Also
Date, POSIXt, difftime, Ops
Examples

    ## Date
    as.Date("2038-01-19") > as.Date("1970-01-01")
    as.Date("2038-01-19") - as.Date("1970-01-01")
    as.Date("1970-01-01") + (as.Date("2038-01-19") - as.Date("1970-01-01"))
    as.Date("1970-01-01") + 1
    as.Date("1970-01-01") + as.difftime(1, units = "weeks")
    ## POSIXt
    as.POSIXct("2038-01-19 03:14:07") > as.POSIXct("1970-01-01 00:00:00")
    as.POSIXct("2038-01-19 03:14:07") - as.POSIXct("1970-01-01 00:00:00")
    as.POSIXct("1970-01-01 00:00:00") + (2^31 - 1)
    as.POSIXct("1970-01-01 00:00:00") + 1
    as.POSIXct("1970-01-01 00:00:00") + as.difftime(1, units = "weeks")
    ## difftime
    (df1 <- as.difftime(12, units = "hours"))
    (df2 <- as.difftime(1, units = "days"))
    df1 * 2 == df2
    df1 + 12
    df2 / 2

Package base version 6.1.5-18
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