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data management question

3 messages · Sebastián Daza, Berend Hasselman, David Winsemius

Original
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.
Berend Hasselman
#
On 08-02-2012, at 06:23, Sebasti?n Daza wrote:

            

      
      
      
    

        
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

  
  


  


      

    

    

      
      

        


  

        

      David Winsemius
    

    

      
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On Feb 8, 2012, at 12:23 AM, Sebasti?n Daza wrote:

        

            

      
      
      
    

        
You should get in the habit of offering complete examples.

?cumprod would seem likely helpful.