[R] adding 1 month to a date

2005-10-11 Thread t c
Within an R dataset, I have a date field called “date_”. (The dates are in the format “-MM-DD”, e.g. “1995-12-01”.) How can I add or subtract “1 month” from this date, to get “1996-01-01” or “ “1995-11-01”. - [[alternative H

Re: [R] adding 1 month to a date

2005-10-11 Thread Marc Schwartz
On Tue, 2005-10-11 at 16:26 -0700, t c wrote: > Within an R dataset, I have a date field called date_. (The dates are > in the format -MM-DD, e.g. 1995-12-01.) > How can I add or subtract 1 month from this date, to get 1996-01-01 or > 1995-11-01. There might be an easier way to do this, but

Re: [R] adding 1 month to a date

2005-10-12 Thread bogdan romocea
s. > -Original Message- > From: Marc Schwartz [mailto:[EMAIL PROTECTED] > Sent: Tuesday, October 11, 2005 10:16 PM > To: t c > Cc: r-help@stat.math.ethz.ch > Subject: Re: [R] adding 1 month to a date > > > On Tue, 2005-10-11 at 16:26 -0700, t c wrote: > > Withi

Re: [R] adding 1 month to a date

2005-10-12 Thread Prof Brian Ripley
TED] >> Sent: Tuesday, October 11, 2005 10:16 PM >> To: t c >> Cc: r-help@stat.math.ethz.ch >> Subject: Re: [R] adding 1 month to a date >> >> >> On Tue, 2005-10-11 at 16:26 -0700, t c wrote: >>> Within an R dataset, I have a date field called date_. >&

Re: [R] adding 1 month to a date

2005-10-12 Thread Marc Schwartz
eneral, as a month is not generally of 30 days (including > in your example). > > seq.Date is a good way to do this. > > > > > > >> -Original Message- > >> From: Marc Schwartz [mailto:[EMAIL PROTECTED] > >> Sent: Tuesday, October 11, 2005

Re: [R] adding 1 month to a date

2005-10-12 Thread Jim Porzak
> > > where 30*24*3600 = 30 days expressed in seconds. > > > > > > Sorry, not in general, as a month is not generally of 30 days (including > > > in your example). > > > > > > seq.Date is a good way to do this. > > > > > > > &g

Re: [R] adding 1 month to a date

2005-10-12 Thread David Forrest
On Wed, 12 Oct 2005, Jim Porzak wrote: > OTOH, > > > seq(as.Date("2004-01-31"), by = "month", length = 14) > [1] "2004-01-31" "2004-03-02" "2004-03-31" "2004-05-01" "2004-05-31" > [6] "2004-07-01" "2004-07-31" "2004-08-31" "2004-10-01" "2004-10-31" > [11] "2004-12-01" "2004-12-31" "2005-01-

Re: [R] adding 1 month to a date

2005-10-12 Thread t c
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 : , 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 Gro

Re: [R] adding 1 month to a date

2005-10-12 Thread t c
Thanks. How do I use this to calculate a new variable (e.g."data$next_month") from an existing variable (e.g."Data$date_"). I tried : , 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 Gr

Re: [R] adding 1 month to a date

2005-10-12 Thread Gabor Grothendieck
quot;1995-12-01 08:00:00",format="%Y-%m-%d %H:%M:%S") + > > > > > 30*24*3600 > > > > > where 30*24*3600 = 30 days expressed in seconds. > > > > > > > > Sorry, not in general, as a month is not generally of 30 days (including > >

Re: [R] adding 1 month to a date

2005-10-12 Thread Gabor Grothendieck
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 <[EMAIL PROTECTED]> wrote: > > Within an R dataset, I have a date field called "date_". (The dates are in > the format "-

Re: [R] adding 1 month to a date

2005-10-12 Thread Gabor Grothendieck
Try this. Note that mapply strips off the class which is why we set up dd with the correct class and then just replaced the values. # test data d <- as.Date("2005-1-1") + seq(0,90,30) # calculations, dd is the result next.month <- function(x) seq(x, len = 2, by = "months")[2] dd <- d dd[] <- mapp