[R] coercion of LHS to a list

Diego Kuonen Diego at kuonen.com
Tue Nov 7 18:07:41 CET 2000


Pete Phillips wrote:
> If I try to create a new column at the R command line, as follows:
> 
> nebdata$logconc<-nebdata$Volt*nebcal.fm$coefficients[2]+nebcal.fm$coefficients[1]

why not simply take the following:

 nebdata <- data.frame(nebdata,
                       logconc = nebdata$Volt*nebcal.fm$coefficients[2]
                       +nebcal.fm$coefficients[1])

> Also, is it possible for me to reference a single figure in the data
> frame eg: the intersect of Volt and ABal (0.4208) without having to
> resort to this:
>          nebdata[1:1, c(2)]

you can think of a data frame to be like a matrix, i.e. if u want to
access the element in the i-th line and j-th column, you simply take
  
   nebdata[i, j]

for instance in your case

   nebdata[1, 2]

or

   nebdata[nebdata$Volt=="ABal", 2]

or by attaching the data frame

   attach(nebdata)
   nebdata[Volt=="ABal", 2]
   detach(nebdata)

Greets

  Diego

-- 
Diego Kuonen      http://wap.kuonen.com     http://stat.kuonen.com
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