Hello again, Let say I have an non-negative integer vector (which may be random): Vec <- c(0, 13, 10, 4) And I have a date:> Date <- as.Date(Sys.time()) > Date[1] "2013-03-09" Using these 2 information, I want to get following date-vector: New_Vec <- c("2013-03-01", "2014-04-01", "2014-01-01", "2013-07-01") Basically the month-difference between 'New_Vec' and 'Date' will be 'Vec ' Is there any R function to do it programmatically? Thanks for your help.
On Sat, Mar 9, 2013 at 11:41 AM, Christofer Bogaso < bogaso.christofer@gmail.com> wrote:> Hello again, > > Let say I have an non-negative integer vector (which may be random): > > Vec <- c(0, 13, 10, 4) > > And I have a date: > > > Date <- as.Date(Sys.time()) > > Date > [1] "2013-03-09" > > > > Using these 2 information, I want to get following date-vector: > > New_Vec <- c("2013-03-01", "2014-04-01", "2014-01-01", "2013-07-01") > > Basically the month-difference between 'New_Vec' and 'Date' will be 'Vec ' > > Is there any R function to do it programmatically? > >Do you always want the first day of the month? If so, I think library(zoo) ?yearmon is what you are looking for. Specifically: convert to yearmon, add in the month difference, convert back to date to get the first day of the month. Cheers, MW> > Thanks for your help. > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide > http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. >[[alternative HTML version deleted]]
Hello,
I don't believe there's such a function, but you can write one.
Date <- as.Date(Sys.time())
New_Vec <- c("2013-03-01", "2014-04-01",
"2014-01-01", "2013-07-01")
New_Vec <- as.Date(New_Vec)
Vec <- c(0, 13, 10, 4)
plusmonths <- function(x, y){
s <- as.integer(format(x, "%m")) + y
yx <- as.integer(format(x, "%Y")) + (s %/% 12)
as.Date(paste(yx, s %% 12, "01", sep = "-"))
}
pm <- plusmonths(Date, Vec)
identical(New_Vec, pm) # TRUE
Hope this helps,
Rui Barradas
Em 09-03-2013 11:41, Christofer Bogaso escreveu:> Hello again,
>
> Let say I have an non-negative integer vector (which may be random):
>
> Vec <- c(0, 13, 10, 4)
>
> And I have a date:
>
>> Date <- as.Date(Sys.time())
>> Date
> [1] "2013-03-09"
>
>
>
> Using these 2 information, I want to get following date-vector:
>
> New_Vec <- c("2013-03-01", "2014-04-01",
"2014-01-01", "2013-07-01")
>
> Basically the month-difference between 'New_Vec' and 'Date'
will be 'Vec '
>
> Is there any R function to do it programmatically?
>
>
> Thanks for your help.
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
Hi, You could try this: library(lubridate) ?res<-as.Date(dmy(format(Date-8, "%d-%m-%Y"))+months(Vec)) res #[1] "2013-03-01" "2014-04-01" "2014-01-01" "2013-07-01" A.K. ----- Original Message ----- From: Christofer Bogaso <bogaso.christofer at gmail.com> To: r-help <r-help at r-project.org> Cc: Sent: Saturday, March 9, 2013 6:41 AM Subject: [R] Calculation with date Hello again, Let say I have an non-negative integer vector (which may be random): Vec <- c(0, 13, 10, 4) And I have a date:> Date <- as.Date(Sys.time()) > Date[1] "2013-03-09" Using these 2 information, I want to get following date-vector: New_Vec <- c("2013-03-01", "2014-04-01", "2014-01-01", "2013-07-01") Basically the month-difference between 'New_Vec' and 'Date' will be 'Vec ' Is there any R function to do it programmatically? Thanks for your help. ______________________________________________ R-help at r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
The lubridate and seq solutions work because they rely on your specification that the returned date be the first day of the desired subsequent months. Without that requirement they would not always work. For example, if you wanted to add Vec months to the last day of March rather than the first day, the second date produced by those solutions is in May which the month following the desired month (April):> Date <- as.Date("2013-03-31") > library(lubridate) > as.Date(dmy(format(Date-8, "%d-%m-%Y"))+months(Vec))1 parsed with %d-%m-%Y [1] "2013-03-31" "2014-05-01" "2014-01-31" "2013-07-31" and> seq(Date, length=diff(range(Vec))+1, by="month")[Vec+1][1] "2013-03-31" "2014-05-01" "2014-01-31" "2013-07-31" The mondate package does date arithmetic in months and is guaranteed to give you a date in your desired number of subsequent months (or previous months, btw):> library(mondate) > as.Date(mondate(Date) + Vec)[1] "2013-03-31" "2014-04-30" "2014-01-31" "2013-07-31" To get the first day of the month, you could simply subtract the day number of the result, as shown in previous replies:> res <- as.Date(mondate(Date) + Vec) > res - as.POSIXlt(res)$mday + 1[1] "2013-03-01" "2014-04-01" "2014-01-01" "2013-07-01" or you could do the calculation with mondate's as follows> res <- mondate(Date) + Vec > as.Date(mondate.ymd(year(res), month(res), 1))[1] "2013-03-01" "2014-04-01" "2014-01-01" "2013-07-01" Hope that helps, Dan ================= Message: 16 Date: Sat, 9 Mar 2013 08:37:23 -0800 From: David Winsemius <dwinsemius at comcast.net> To: Rui Barradas <ruipbarradas at sapo.pt> Cc: r-help <r-help at r-project.org> Subject: Re: [R] Calculation with date Message-ID: <01E8683D-60BE-4750-AB1B-6047162CC175 at comcast.net> Content-Type: text/plain; charset=us-ascii On Mar 9, 2013, at 4:24 AM, Rui Barradas wrote:> Hello, > > I don't believe there's such a function, but you can write one.I beg to disagree. The seq.Date function lets one create sequences by month. The only added twist in this case is to subract to the beginning of the current month:> seq( Date- as.POSIXlt(Date)$mday+1, length=diff(range(Vec))+1, by="month")[Vec+1][1] "2013-03-01" "2014-04-01" "2014-01-01" "2013-07-01"> > Date <- as.Date(Sys.time()) > New_Vec <- c("2013-03-01", "2014-04-01", "2014-01-01", "2013-07-01") > New_Vec <- as.Date(New_Vec) > Vec <- c(0, 13, 10, 4) > > > plusmonths <- function(x, y){ > s <- as.integer(format(x, "%m")) + y > yx <- as.integer(format(x, "%Y")) + (s %/% 12) > as.Date(paste(yx, s %% 12, "01", sep = "-")) > } > pm <- plusmonths(Date, Vec) > > identical(New_Vec, pm) # TRUE > > > Hope this helps, > > Rui Barradas > > Em 09-03-2013 11:41, Christofer Bogaso escreveu: >> Hello again, >> >> Let say I have an non-negative integer vector (which may be random): >> >> Vec <- c(0, 13, 10, 4) >> >> And I have a date: >> >>> Date <- as.Date(Sys.time()) >>> Date >> [1] "2013-03-09" >> >> >> >> Using these 2 information, I want to get following date-vector: >> >> New_Vec <- c("2013-03-01", "2014-04-01", "2014-01-01", "2013-07-01") >> >> Basically the month-difference between 'New_Vec' and 'Date' will be 'Vec ' >> >> Is there any R function to do it programmatically? >> >> >> Thanks for your help. >> >> ______________________________________________ >> R-help at r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-help >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html >> and provide commented, minimal, self-contained, reproducible code. >> > > ______________________________________________ > R-help at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code.David Winsemius Alameda, CA, USA