Question

I’ve been trying for a while now to produce a code that brings me a new vector of the sum of the 25 previous rows for an original vector.

So if we say I have a variable Y with 500 rows and I would like a running sum, in a new vector, which contains the sum of rows [1:25] then [2:26] for the length of Y, such as this:

y<-1:500
runsum<-function(x){
   cumsum(x)-cumsum(x[26:length(x)])
}

new<-runsum(y)

I’ve tried using some different functions here and then even using the apply functions on top but none seem to produce the right answers….

Would anyone be able to help? I realise it’s probably very easy for many of the community here but any help would be appreciated

Thanks

Answer 1

This function calculates the sum of the 24 preceding values and the actual value:

 movsum <- function(x,n=25){filter(x,rep(1,n), sides=1)}

It is easy to adapt to sum only preceding values, if this is what you really want.