i is an element in zn so replace zn[i] with just i
for (i in zn){
treat$su[treat$Zugnacht==as.POSIXct(i, "UTC")] <-
min(treat$Vollzeit[treat$Zugnacht==as.POSIXct(zni, "UTC")])
treat$sa[treat$Zugnacht==as.POSIXct(zni, "UTC")] <-
max(treat$Vollzeit[treat$Zugnacht==as.POSIXct(zni, "UTC")])
}
If you want to keep i as an index you need something like:
for(i in 1:length(i))
{
#do stuff on zn[i]
}
On Thu, 2014-05-08 at 14:19 -0700, peregrine wrote:
> Hallo,
>
> I have a table in which I would like to insert the min and max values of
> another column (date and time in as.POSIXct Format).
>
> This is my row table, where "su" and "sa" are still the same as "Vollzeit":
>
> head(treat)
> Vollzeit Datum Zugnacht su
>
> sa
> 2 2013-09-09 20:15:00 2013-09-09 2013-09-09 2013-09-09 20:15:00 2013-09-09
> 20:15:00
> 3 2013-09-09 20:30:00 2013-09-09 2013-09-09 2013-09-09 20:30:00 2013-09-09
> 20:30:00
> 4 2013-09-09 20:45:00 2013-09-09 2013-09-09 2013-09-09 20:45:00 2013-09-09
> 20:45:00
> 5 2013-09-09 21:00:00 2013-09-09 2013-09-09 2013-09-09 21:00:00 2013-09-09
> 21:00:00
> 6 2013-09-09 21:15:00 2013-09-09 2013-09-09 2013-09-09 21:15:00 2013-09-09
> 21:15:00
> 7 2013-09-09 21:30:00 2013-09-09 2013-09-09 2013-09-09 21:30:00 2013-09-09
> 21:30:00
>
> Now I want to insert the minimum value of "Vollzeit" for each date in
> "Zugnacht" into the column "su" and the maximum value of "Vollzeit" for each
> date in "Zugnacht" into the column "sa". If I do it like this, it does
> exactly what I want:
>
> zn <- unique(treat$Zugnacht)
> i=zn[1]
> treat$su[treat$Zugnacht==as.POSIXct(i, "UTC")] <-
> min(treat$Vollzeit[treat$Zugnacht==as.POSIXct(i, "UTC")])
> treat$sa[treat$Zugnacht==as.POSIXct(i, "UTC")] <-
> max(treat$Vollzeit[treat$Zugnacht==as.POSIXct(i, "UTC")])
>
> This is the result for the first date in "Zugnacht":
> head(treat)
> Vollzeit Datum Zugnacht su
>
> sa
> 2 2013-09-09 20:15:00 2013-09-09 2013-09-09 2013-09-09 20:15:00 2013-09-10
> 04:30:00
> 3 2013-09-09 20:30:00 2013-09-09 2013-09-09 2013-09-09 20:15:00 2013-09-10
> 04:30:00
> 4 2013-09-09 20:45:00 2013-09-09 2013-09-09 2013-09-09 20:15:00 2013-09-10
> 04:30:00
> 5 2013-09-09 21:00:00 2013-09-09 2013-09-09 2013-09-09 20:15:00 2013-09-10
> 04:30:00
> 6 2013-09-09 21:15:00 2013-09-09 2013-09-09 2013-09-09 20:15:00 2013-09-10
> 04:30:00
> 7 2013-09-09 21:30:00 2013-09-09 2013-09-09 2013-09-09 20:15:00 2013-09-10
> 04:30:00
>
>
> However I am not able to create a loop that runs over all 113 dates in zn. I
> tried this, but it does not work. Can anybody help, please?
>
> for (i in zn){
> treat$su[treat$Zugnacht==as.POSIXct(zn[i], "UTC")] <-
> min(treat$Vollzeit[treat$Zugnacht==as.POSIXct(zn[i], "UTC")])
> treat$sa[treat$Zugnacht==as.POSIXct(zn[i], "UTC")] <-
> max(treat$Vollzeit[treat$Zugnacht==as.POSIXct(zn[i], "UTC")])
> }
>
> Kind regards
> Christiane
>
>
>
>
> --
> View this message in context:
> http://r.789695.n4.nabble.com/How-to-write-a-loop-in-which-i-has-to-be-in-POSIX-format-tp4690212.html
> Sent from the R help mailing list archive at Nabble.com.
>
> ______________________________________________
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> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
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