How to replace the top 1% of the data with a new value in R?

Question

In R, given a set of numerical data, how do I decide the top 1% of these data, and replace them with a new value, say, e.g. $10^{10}$

Answer 1

You could do this:

### x will be whatever variable you want to do this to. I'm replacing 
### the top 1% with 1e10. 
qnt = quantile(x,.99)
w = which(x >= qnt) 
x[w] = 1e10

More generally implemented as a function:

### x is the input data. This function replaces the top 'perc' percent
### with the value 'rp'. 
replace.top = function(x, perc, rp)
{
   qnt = quantile(x,1-perc)
   w = which(x >= qnt) 
   x[w] = rp
   return(x)
}