[R] find date between two other dates

[Rui Barradas]

Hello,

You can use a function that returns the number you want, not a logical 
value.
But first, it's a bad idea to have a data.frame and a vector with the 
same name, so, in what follows, I've altered the df name.

ddate <-  c("29/12/1998 20:00:33", "02/01/1999 05:20:44", "02/01/1999
06:18:36", "02/02/1999 07:06:59", "02/03/1999 07:10:56", "02/03/1999
07:57:18")
ddate <- as.POSIXct(strptime(ddate, "%d/%m/%Y %H:%M:%S"), "GMT")
ddat <- data.frame(ddate=ddate)   # Here, different name.

season.month <- function(x){
     x <- as.integer(format(x, format="%m"))
     ifelse(x == 12L, 1L, x + 1L)
}

season.month(ddate)
ddat$season <- season.month(ddate)
str(ddat)
'data.frame':   6 obs. of  2 variables:
  $ ddate : POSIXct, format: "1998-12-29 20:00:33" "1999-01-02 05:20:44" ...
  $ season: int  1 2 2 3 4 4

ddat
                 ddate season
1 1998-12-29 20:00:33      1
2 1999-01-02 05:20:44      2
3 1999-01-02 06:18:36      2
4 1999-02-02 07:06:59      3
5 1999-03-02 07:10:56      4
6 1999-03-02 07:57:18      4

Hope this helps,

Rui Barradas

Em 05-08-2012 21:30, penguins escreveu:
> Hi,
>
> I am trying to assign "Season" values to dates depending on when they occur.
>
> For example, the following dates would be assigned the following "Season"
> numbers based on the "season" intervals detailed below in the code:
>
> ddate                               Season
> 29/12/1998 20:00:33       1
> 02/01/1999 05:20:44       2
> 02/01/1999 06:18:36       2
> 02/02/1999 07:06:59       3
> 02/03/1999 07:10:56       4
> 02/03/1999 07:57:18       4
>
> My approach so far doesnt work because of the time stamps and is probably
> very long winded. However, to prevent errors I would prefer to keep the date
> formats as dd/mm/yyyy as oppose to a numeric format. Any help on the
> following code would be gratefully recieved:
>   
> ddate <-  c("29/12/1998 20:00:33", "02/01/1999 05:20:44", "02/01/1999
> 06:18:36", "02/02/1999 07:06:59", "02/03/1999 07:10:56", "02/03/1999
> 07:57:18")
> ddate <- as.POSIXct(strptime(ddate, "%d/%m/%Y %H:%M:%S"), "GMT")
>
> is.between<-function(x, a, b) {
>         (x > a) & (b > x)
> }
>
> ddate$s1 <- is.between(ddate, 01/12/1998 00:00:00, 31/12/1998 23:59:59)
> ddate$s2 <- is.between(ddate, 01/01/1999 00:00:00, 31/01/1999 23:59:59)
> ddate$s3 <- is.between(ddate, 01/02/1999 00:00:00, 28/02/1999 23:59:59)
> ddate$s4 <- is.between(ddate, 01/03/1999 00:00:00, 31/03/1999 23:59:59)
>
> Many thanks
>
>
>
> --
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