[R] converting to a language object

[Marc Schwartz]

Arnab mukherji wrote:
> Hi,
> 
> I have a query about the following:
> 
> CONTEXT: if we define:
> 
> eq <- y ~ x1 + x2
> 
> then is.language(eq) returns true. this works perfectly with commands
> such as lm(eq,data=my.data)
> 
> THE PROBLEM: Now I have a big data set with about 2000 independent
> variables. So I tried to automate this. I can pick off the names of
> the variables and insert a plus in between them and get a string.
> Thus I have
> 
> eq<- y ~ " x1 + x2 + ... +x2000" or eq<-"y ~ " x1 + x2 + ... +x2000"
> 
> from either case how can I typecast eq into a langugae object and get
> the lm command to work ?
> 
> Does anyone have any suggestions?
> 
> thanks
> 
> Arnab.


Arnab,

Once you have your full formula string constructed you can use:

eq <- eval(parse(text = string))

This will put the model formula into eq.


For example try:

eq <- eval(parse(text = "y ~ x1 + x2"))


See ?eval and ?parse for more information.

Hope that helps.


Regards,

Marc Schwartz