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subset select within a function

3 messages · juli g. pausas, Sean Davis, Peter Wolf

juli g. pausas
# 
Dear all,
I'd like to subset a df within a function, and use select for choosing 
the variable. Something like (simplified example):

mydf <- data.frame(a= 0:9, b= 10:19)

ttt <- function(vv) {
  tmpdf <- subset(mydf, select= vv)
  mean(tmpdf$vv)
}

ttt(mydf$b)

But this is not the correct way. Any help?
Thanks in advance

Juli
Sean Davis
# 
Juli,

Check again in the help about how to use the select parameter.  You need to
pass the column name for the column of interest, not the actual column.
Also, your tmpdf will already have the column selected, so there is no need
to index the column further, at least in this toy example.  In this case, I
think you could use something like:
function(vv) {
tmpdf <- subset(mydf,select=vv)
mean(tmpdf)
}
b
14.5

Sean
On 1/21/04 6:56 AM, "juli g. pausas" <juli at ceam.es> wrote:

            

      
      
      
    

        

      
      
    

  
  


  


      

    

    

      
      

        


  

        

      Peter Wolf
    

    

      
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juli g. pausas wrote:

        

            

      
      
      
    

        

      
      
    

        
are you looking for something like:

mydf <- data.frame(a= 0:9, b= 10:19)
ttt <- function(vv) {
 tmpdf <- subset(mydf, select= vv)
 lapply(tmpdf,mean)
}
ttt("b") $b
[1] 14.5
 > ttt(c("a","b"))
$a
[1] 4.5
$b
[1] 14.5

??

Peter