try this:
> set.seed(1)
> day= rep(1:30, each=10)
> n= length(day); x= c(1:24)
> time= sample(x, 300, replace= T)
> light= rep(c(20,10,6,0,0,0,0,0,8,20), 30)
> d=data.frame(day,time,light)
>
> # create a dawn/dusk column to mark where it happens
> d$dawn <- c(FALSE, (head(d$light, -1) < 2) & (tail(d$light, -1) > 2))
> d$dusk <- c((head(d$light, -1) > 2) & (tail(d$light, -1) < 2), FALSE)
>
> # now split and recombine to get the values for the day
> result <- do.call(rbind, lapply(split(d, d$day), function(.day){
+ # create new dataframe with the values
+ cbind(.day[, c('day', 'time', 'light')]
+ , dawn = .day$time[.day$dawn]
+ , dusk = .day$time[.day$dusk]
+ )
+ }))
>
>
>
> result
day time light dawn dusk
1.1 1 7 20 16 14
1.2 1 9 10 16 14
1.3 1 14 6 16 14
1.4 1 22 0 16 14
1.5 1 5 0 16 14
1.6 1 22 0 16 14
1.7 1 23 0 16 14
1.8 1 16 0 16 14
1.9 1 16 8 16 14
1.10 1 2 20 16 14
2.11 2 5 20 10 17
2.12 2 5 10 10 17
2.13 2 17 6 10 17
2.14 2 10 0 10 17
2.15 2 19 0 10 17
2.16 2 12 0 10 17
2.17 2 18 0 10 17
2.18 2 24 0 10 17
2.19 2 10 8 10 17
2.20 2 19 20 10 17
3.21 3 23 20 21 16
3.22 3 6 10 21 16
3.23 3 16 6 21 16
3.24 3 4 0 21 16
3.25 3 7 0 21 16
3.26 3 10 0 21 16
3.27 3 1 0 21 16
3.28 3 10 0 21 16
3.29 3 21 8 21 16
3.30 3 9 20 21 16
4.31 4 12 20 18 12
4.32 4 15 10 18 12
4.33 4 12 6 18 12
4.34 4 5 0 18 12
4.35 4 20 0 18 12
4.36 4 17 0 18 12
4.37 4 20 0 18 12
4.38 4 3 0 18 12
4.39 4 18 8 18 12
4.40 4 10 20 18 12
On Sun, Jul 15, 2012 at 12:32 PM, Santiago Guallar <sgual...@yahoo.com> wrote:
> Hi,
>
> I have a dataset which contains several time records for a number of days,
> plus a variable (light) that allows to determine night time (lihgt= 0) and
> daytime (light> 0). I need to obtain get dusk time and dawn time for each day
> and place them in two columns.
>
> This is the starting point (d):
> day time light
> 1 1 20
> 1 12 10
> 1 11 6
> 1 9 0
> 1 6 0
> 1 12 0
> ...
> 30 8 0
> 30 3 0
> 30 8 0
> 30 3 0
> 30 8 8
> 30 9 20
>
>
> And this what I want to get:
> day time light dusk dawn
> 1 1 20 11 10
> 1 12 10 11 10
> 1 11 6 11 10
> 1 9 0 11 10
> 1 6 0 11 10
> 1 12 0 11 10
> ...
> 30 8 0 9 5
> 30 3 0 9 5
> 30 8 0 9 5
> 30 3 0 9 5
> 30 8 8 9 5
> 30 9 20 9 5
>
> This is the code for data frame d:
> day= rep(1:30, each=10)
> n= length(dia); x= c(1:24)
> time= sample(x, 300, replace= T)
> light= rep(c(20,10,6,0,0,0,0,0,8,20), 30)
> d=data.frame(day,time,light)
>
> I'd need to impose a double condition like the next but if does not take more
> than one:
> attach(d)
> for (i in 1: n){
> if (light[i-1]>2 & light[i]<2){
> d$dusk<- time[i-1]
> }
> if (light[i-1]<2 & light[i]>2){
> d$dawn<- time[i]
> }
> }
> detach(d)
> d
>
> Thank you for your help
> [[alternative HTML version deleted]]
>
>
> ______________________________________________
> 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.
>
--
Jim Holtman
Data Munger Guru
What is the problem that you are trying to solve?
Tell me what you want to do, not how you want to do it.
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