[R] Sequences

[Bernardo Rangel Tura]

On Tue, 2009-04-07 at 05:16 -0700, Melissa2k9 wrote:
> Hi,
> 
> I am trying to make a sequence and am  using a for loop for this. I want to
> start off with an initial value ie S[0]=0 then use the loop to create other
> values. This is what I have so far but I just keep getting error messages.
> 
> #To calculate the culmulative sums:
> 
> s<-rep(0,207)                                #as this is the length of the
> vector I know I will have
> s<-as.vector(s)
> s[0]<-0
> for (i in 1:length(lambs))                    # where lambs is a vector of
> length 207 consisting of temperature 
>                                                                     values
> 
> 
> {
> 	s[i]<-s[i-1]-mean(lambs)
> }
> 
> I continually get the error message: 
> 
> Error in s[i] <- s[i - 1] - mean(lambs) : replacement has length zero
> 
> 
> When I merely use s[i]<-i-mean(lambs) it works so there is obviously
> something wrong with the s[i-1] but i cant see what. All I want is for each
> S[i] to be the previous value for S - the mean.

Hi Melissa,

I think this is a index problem ...

your code is:

s<-rep(0,207)   
s<-as.vector(s)
s[0]<-0
for (i in 1:length(lambs)){
        s[i]<-s[i-1]-mean(lambs)
}

But try this code:

s<-rep(0,207)   
s<-as.vector(s)
s[1]<-0 # not s[0]
for (i in 2:length(lambs)){ #not 1:length(lambs)
        s[i]<-s[i-1]-mean(lambs)
}

The vector in R begin in 1 not in 0...

-- 
Bernardo Rangel Tura, M.D,MPH,Ph.D
National Institute of Cardiology
Brazil