[R] help on date dataset

[Rui Barradas]

Hello,

If I understand it correctly, you have a data.frame whose first column 
is a date and want to extract all lines between two given dates. If so, 
try the following. Note that I've added two new arguments to your function.

dat <- read.table(text="
DATE                       PAYS         nb_pays.ILI.
1   24/04/2009                 usa            0
2   24/04/2009                 usa            0
3   24/04/2009             Mexique            0
4   24/04/2009             Mexique            0
5   26/04/2009                 usa           20
6   26/04/2009                 usa           20
7   26/04/2009                 usa           20
8   26/04/2009                 usa           20
9   26/04/2009                 usa           20
10  26/04/2009             Mexique           18
11  27/04/2009                 usa           40
12  27/04/2009             Mexique           26
13  27/04/2009              Canada            6
14  27/04/2009               Spain            1
15  28/04/2009             Canada             6
", header = TRUE)

dat
dat$DATE <- as.Date(dat$DATE, format = "%d/%m/%Y")

extraction <- function(DF, date1, date2, format = "%Y-%m-%d"){
     date1 <- as.Date(date1, format)
     date2 <- as.Date(date2, format)
     idx <- date1 < DF[[1]] & DF[[1]] < date2
     DF[idx, ]
}

date1 <- "04 03 2009"
date2 <- "04 12 2009"
extraction(dat, date1, date2, format = "%d %m %Y")


Hope this helps,

Rui Barradas
Em 10-11-2012 13:21, anoumou escreveu:
> Hi everybody,
> I am beginer in R and I need your precious help.
> I want to create a small function  in R as in sas to retrieve date.
> I have a file with data that import in R.
>   DATE                       PAYS         nb_pays.ILI.
> 1   24/04/2009                 usa            0
> 2   24/04/2009                 usa            0
> 3   24/04/2009             Mexique            0
> 4   24/04/2009             Mexique            0
> 5   26/04/2009                 usa           20
> 6   26/04/2009                 usa           20
> 7   26/04/2009                 usa           20
> 8   26/04/2009                 usa           20
> 9   26/04/2009                 usa           20
> 10  26/04/2009             Mexique           18
> 11  27/04/2009                 usa           40
> 12  27/04/2009             Mexique           26
> 13  27/04/2009              Canada            6
> 14  27/04/2009               Spain            1
> 15  28/04/2009             Canada             6
>
> I want to create something like that:
> •	When entering two dates date1,date2 in the fuction extraction.
> The result must be: a  new subdata  with one line  per date , per PAYS,per
> nb_pays.ILI (by summing all the number in variable nb_pays.ILI per date,per
> country)  and the date must be between date1 and date2.
> I sart to do somethings like that
> extraction=function(date1,date2)
>    {date<-derdata[["DATE"]]
>     date
>     sort(date)
>     PAYS<-derdata[["PAYS"]]
>     nb_pays.ILI<-derdata[["nb_pays.ILI."]]
>     test1<-as.character(date,"%d %m %y")
>     test1
>     #the first date
>     date1<- "04 03 2009"
>     date1 <- strptime(date1, "%d %m %Y")
>     date1
>     unlist(unclass(date1))
>     date1 <- as.POSIXct(date1)
>     date1
>     attributes(date1)
>     date1 <-unclass(date1)
>     date1
>     
>     #the second date
>     date2<- "04 12 2009"
>     date2 <- strptime(date2, "%d %m %Y")
>     date2
>     unlist(unclass(date2))
>     date2 <- as.POSIXct(date2)
>     date2
>     attributes(date2)
>     date2 <-unclass(date2)
>     date2
>     B1<- as.POSIXct(test1)
>     B1 <-unclass(B1)
>     B1
>     B4 <- B1[(B1>date1) & (B1<date2)]
>     B4
>    
> }
>
>
>
>
> --
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>
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