[R] data management question

[Sebastián Daza]

Hi everyone,
I would like to have a function to compute some values in a dataset.
First, I have to define a value for the lx variable in row 1 (e.g.,
100,000), npx is a given proportion. lx of row 2 is equal to lx of row
1 times npx of row 1. I can do this row by row...

data[1,"lx"]  <- 100000
data[2,"lx"]  <- data[1,"lx"]*data[1,"npx"]
data[3,"lx"]  <- data[2,"lx"]*data[2,"npx"]
data[4,"lx"]  <- data[3,"lx"]*data[3,"npx"]
...
data[19,"lx"]  <- data[18,"lx"]*data[18,"npx"]

Any ideas about how to define this in a function or in a more systematic way?
Thank you in advance.

-- 
Sebastián Daza