I have spent a significant amount of time searching for an answer with little luck. I have some time series data and need to collapse and create a rolling mean of every nth row in that data. It looks like this is possible in zoo and maybe hmisc and i am sure other packages. I need to average rows 1,2,3 then 3,4,5 then 5,6,7 and so on. my data looks like such and has thousands of observations:
id time x.1 x.2 y.1 y.2
10 1 22 19 0 -.5
10 2 27 44 -1 0
10 3 19 13 0 -1.5
10 4 7 22 .5 1
10 5 -15 5 .33 2
10 6 3 17 1 .33
10 7 6 -2 0 0
10 8 44 25 0 0
10 9 27 12 1 -.5
10 10 2 11 2 1
I would like it to look like this when complete:
id time x.1 x.2 y.1 y.2
10 1 22.66 25.33 -.33 -.66
10 2 3.66 13.33 .27 .50
The time var 1 would actually be times 1,2,3 averaged and 2 would be 3,4,5 averaged but at this point the time var would not be important to keep. I would need to group by id as it does change eventually. The only way I could figure out how to do this successfully was to use Lag() and make new rows lead by 1 and another by 2 then take average across columns. after that you have to delete every other row
1 NA NA
2 1 NA
3 2 1
4 3 2
5 4 3
use the 123 and 345 and remove 234... to do this for each var would be outrageous especially as i gather new data.
any ideas? help would be much appreciated
something like this maybe?
# sample data
id <- c(10,10,10,10,10,10)
time <- c(1,2,3,4,5,6)
x1 <- c(22,27,19,7,-15,3)
x2 <- c(19,44,13,22,5,17)
df <- data.frame(id,time,x1,x2)
means <- data.frame(rollmean(df[,c(1,3:NCOL(df))], 3))
means <- means[c(T,F),]
means$time <- seq(1:NROW(means))
row.names(means) <- 1:NROW(means)
> means
id x1 x2 time
1 10 22.666667 25.33333 1
2 10 3.666667 13.33333 2