Hi all,

I am somewhat new to R, and i have this piece of code which generates a variable that i don't know the type for. Are there any introspection facility in R which will tell me which type this variable belongs to?

The following illustrates the property of this variable:

I am working on linear model selection, and the resource I have is lm result from another model. Now I want to retrieve the lm call by the command summary(model)$call so that I don't need to hardcode the model structure. However, since I have to change the dataset, I need to do a bit of modification on the "string", but apparently it is not a simple string. I wonder if there is any command similar to string.replace so that I can manipulate this variable from the variable $call.

Thanks

> str<-summary(rdnM)$call
> str
lm(formula = y ~ x1, data = rdndat)
> str[1]
lm()
> str[2]
y ~ x1()
> str[3]
rdndat()
> str[3] <- data
Warning message:
In str[3] <- data :
  number of items to replace is not a multiple of replacement length
> str
lm(formula = y ~ x1, data = c(10, 20, 30, 40))
> str<-summary(rdnM)$call
> str
lm(formula = y ~ x1, data = rdndat)
> str[3] <- 'data'
> str
lm(formula = y ~ x1, data = "data")
> str<-summary(rdnM)$call
> type str
Error: unexpected symbol in "type str"
>