[R] newbie:looking for an efficient way to compute distance vector

papagenic nabble at dejademain.com
Wed Jan 23 17:32:11 CET 2008

dear experts,

I am new to R and am trying to compute a vector y from  a vector x where :
y[i] = sign(x[j]-x[i])*(j-i)  with j the first index after i where
abs(x[j]-x[i]) > to a given step
y[i] is 0 if there is no such j

I can write this in R as follows
for(i in 1:length(x)) {
   for(j in i:length(x)) {
      if (abs(x[j]-x[i]) > step) {

but I wonder if there is a more efficient way to write this. I understand
explicit looping can often be avoided in R using vector notation.

Thanks for your help
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