Thanks.  How do I se thsi to calculate a new variable (e.g."data$next_month") from an existing variable (e.g."Data$date_").  
 
I tried : <data$next_month<-seq(as.Date(data$date_), len = 2, by = "month")[2]>,
 
but get the following error message:   "Error in seq.Date(as.Date(data$date), len = 2, by = "1 month") : 'from' must be of length 1"
 
Thanks.



Gabor Grothendieck <ggrothendieck@gmail.com> wrote:
Try this:

seq(as.Date("2005-01-15"), len = 2, by = "month")[2]

or here is another approach:

http://finzi.psych.upenn.edu/R/Rhelp02a/archive/61570.html

On 10/11/05, t c wrote:
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> Within an R dataset, I have a date field called "date_". (The dates are in the format "YYYY-MM-DD", e.g. "1995-12-01".)
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> How can I add or subtract "1 month" from this date, to get "1996-01-01" or " "1995-11-01".
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