On Wed, 17 Nov 2004, Andy Bunn wrote:
Is there a way to calculate the number of months between dates?
StartDate <- strptime("01 March 1950", "%d %B %Y") EventDates <- strptime(c("01 April 1955", "01 July 1980"), "%d %B %Y") difftime(EventDates, StartDate)
So, there are 61 months between 01 March 1950 and 01 April 1955. There are 364 months between 01 March 1950 and 01 July 1980. What I want is for there to be a "months" argument to units in difftime. Anybody have a bright idea?
Ah, but months are of variable length.
Is there a better way to approach this than difftime?
Pretty easy: convert to POSIXlt, then use something like
12*x$year + x$month
and subtract those. You could set up a class for "months" and have as.months and a `-' method ....
Thanks in advance, Andy
version_ platform i386-pc-mingw32 arch i386 os mingw32 system i386, mingw32 status major 2 minor 0.0 year 2004 month 10 day 04 language R
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