I know it's not the best practice in R to use the for loop because it doesn't have an enhanced performance. For almost all cases there is a function of the family *apply that solves our problems.

However I'm facing a situation where I don't see a workaround.

I need to calculate percent variation for consecutive values:

pv[1] <- 0
for(i in 2:length(x)) {
  pv[i] <- (x[i] - x[i-1])/x[i-1]
}

So, as you can see, I have to use both the x[i] element, but also the x[i-1] element. By using the *apply functions, I just see how to use the x[i]. Is there anyway I can avoid the forloops?

r loops for-loop
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