[R] How to speed up multiple for loop over list of data frames

[James]

On Oct 17, 2007, at 10:18 AM, Waterman, DG ((David)) wrote:

> I agree. Avoid the lines like:
> iv     = c( iv, min(i, j) )
>
> I had code that was sped up by 70 times after fixing the size of my
> output object before entering a loop.

I'm in the process of replacing that very kind of command.  In my  
case, I'm trying to iterate over a non-integer sequence that doesn't  
begin at 1.

x<-seq(15,25,0.10)

So when I'm iterating over that sequence in my for loop, I don't have  
nice, easy integers that I can also use for the assignment to my  
vector.  Is there a way to know where I am in the for loops progress  
through the vector x, without having to create a separate variable  
that I increment each time the loop executes?  Something along the  
lines of this:

y<-numeric(length(x))
for(i in x) {
      y[i] <- GBSGreeks(Selection = 'delta', TypeFlag="c", S=i, X=20,  
Time=1/12, r=.05, b=.05, sigma=0.4)
}

But that obviously doesn't work.  The vector x is length=101.  My  
vector assignment only works on the 11 integers from 15 to 25.

Is there a clever way to fix this without the use of a separate  
variable to track the loops progress through the vector x and for  
assignment to the equal size y vector?

thanks

James