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When using the "+" operator to increment a date (or date-time), how do i specify that the increment is in days (or months, or weeks, or years)?
> Sys.Date()
[1] "2013-08-23"
> Sys.Date() + 1
[1] "2013-08-24"
> ISOdate(2013,8,23)
[1] "2013-08-23 12:00:00 GMT"
> ISOdate(2013,8,23) + 1
[1] "2013-08-23 12:00:01 GMT"
395
Use the INTNX function to increment dates by intervals. For example, suppose you want to know the date of the start of the week that is six weeks from the week of 17 October 1991. The function INTNX('WEEK','17OCT91'D,6) returns the SAS date value '24NOV1991'D.
To increment a JavaScript date object by one or more days, you can use the combination of setDate() and getDate() methods that are available for any JavaScript Date object instance. The setDate() method allows you to change the date of the date object by passing an integer representing the day of the month.
Use lubridate::days
> require(lubridate)
> Sys.Date()
[1] "2013-08-23"
> Sys.Date() + days(1)
[1] "2013-08-24"
> ISOdate(2013, 8, 23)
[1] "2013-08-23 12:00:00 GMT"
> ISOdate(2013, 8, 23) + days(1)
[1] "2013-08-24 12:00:00 GMT"
With lubridate, you can also use years(), seconds(), etc., or define your own duration.
61
You could use seq for some basic calculations:
today = Sys.Date()
fiveWeeksAhead = tail(seq(today, by = 'week', length = 5), 1)
Or use a package like lubridate if you need more advanced functions.
40
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