[R] data management question
Berend Hasselman
bhh at xs4all.nl
Wed Feb 8 06:39:33 CET 2012
On 08-02-2012, at 06:23, Sebastián Daza wrote:
> 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?
Something like
data[,"lx"] <- 100000 * c(1, cumprod(data[,"npx"]))
In ypur example column "lx" has length 19 and column "npx" appears to have length 18.
So you may have to adjust lengths.
Berend
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