[R] Sequential date by group

[Eric Berger]

dtV <- seq(from=as.Date("1975-01-01"),by='1 month',length=372)
x$dt <- dtV[x$id]

HTH,
Eric


On Mon, Sep 2, 2019 at 8:36 PM Miluji Sb <milujisb using gmail.com> wrote:

> Dear all,
>
> I have a panel data with a large number of groups and the cumulative number
> of months (1 - 372) for January 1995 to December 2005. My goal is to
> extract the corresponding month and year for each observation.
>
> I tried the following;
>
> ###
> x %>%
>   group_by(id) %>%
>   do( data.frame(., Date= seq(.$startdate,
>                               as.Date('1975-01-01'), by = '1 month')))
>
> However, I get the following error;
>
> ###
> Error in seq.default(.$startdate, as.Date("1975-01-01"), by = "1 month") :
>   'from' must be of length 1
>
> Essentially, I want to convert the month number (1-372) to January 1975 to
> December 2005 by ID. Is that possible? Any help will be highly appreciated.
>
> ### Data ###
> x <- structure(list(id = c(1L, 1L, 1L, 2L, 2L, 2L, 3L, 3L, 3L), month =
> c(1L,
> 2L, 3L, 1L, 2L, 3L, 1L, 2L, 3L), startdate = structure(c(1L,
> 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label = "1975-01-01", class = "factor"),
>     enddate = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L), .Label =
> "2005-12-31", class = "factor")), class = "data.frame", row.names = c(NA,
> -9L))
>
> Cross-posted in Statalist - however, Stata seems to have a very inflexible
> date-time structure.
>
> Best regards,
>
> Milu
>
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>
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