Logical function

Dear all,

I'm learning R, with a "classical" programming background. Some hours were
necessary for me to programm the "vector" way.

Here is my dataset :

ds<- data.frame( st=runif(100), st=runif(100),s1=runif(100),mp=runif(100))

I need to generate 2 new variables. First was easy :

ds$n1<- (ds$st>0.38)*1

Second involve a "if" statement.

Here is the "python way" of expressing what I need :

nash<- function(st,s0,s1,mp){
    if (is.na(st) | (st<=0.38)){
        return(0.25)
    }
    if (s0 == mp){
        return(0.25)
    }
    if (s1 == mp){
        return(0.5)
    }
    if (mp == 1){
        return(0.75)
    }
}

I would like to do something like :

ds$n2<- nash(ds)

I mean I would like to add a new variable "n2", whose value depends on the
value of other variables - row per row.

I played with a for loop (don't flame :p), with apply functions and
derivatives, with a logical set, etc....

Can you help me find the "R" way, please ?

Cheers,
--

Olivier Deckmyn | olivier at deckmyn.org | 06 73 40 89 88