In R- for Loop Subsetting

Question

I'm trying to teach myself R and am having a really hard time with loops. I've got the following dataset which extends down to 2008:

"","year","bdeadbes"
"1",1946,295541
"2",1947,396708
"3",1948,472363
"4",1949,434321
"5",1950,546501
"6",1951,393740

I'm trying to figure out how create a loop to subset for years 1951-2008, where for each iteration of the loop, the mean of the last 5 years is calculated and then stored in a new vector. So far, all I've been able to figure out is setting up the storage vector itself:

storage_vec<-rep(length(bd$year[1951:2008]))

I assume that the loop shell should be: for (i in 1:storage_vec){}

but I can't at all figure out how to properly subset the data for my desired operation. Can anyone point me in the right direction?

Answer 1

There are of course more efficient ways of doing this, but using a loop this is one option. The first value is just 393740 because there are no previous values to average with.

dtf <- read.csv(text="
    year,bdeadbes
    1946,295541
    1947,396708
    1948,472363
    1949,434321
    1950,546501
    1951,393740", header=TRUE)

dtf

v <- seq_along(dtf$year)

for (i in length(dtf$year):1) {
    v[i] <- mean(dtf$bdeadbes[(i:(i-5))+5], na.rm=TRUE)
}

rev(v)
# 393740.0 470120.5 458187.3 461731.2 448726.6 423195.7