[R] passing a variable (containing the value of the argument) to a function

[Spencer Graves]

Hi, Peter: 

      How does that compare with the following: 

for (myname in names(myframe)[1:4]){
  mdl <- formula(paste(myname, "~ etc.etc"))
  myfit <- lm(mdl, data=myframe)
  print(summary(myfit))
}

      Or: 

for (myname in names(myframe)[1:4]){
  lm.txt <- paste("lm(", myname, "~ etc.etc, data=myframe)")
   myfit <- eval(parse(text=lm.txt))
  print(summary(myfit))
}

      You are teaching me new uses of "substitute", and I just wonder 
about the relative advantages and disadvantages of the different 
approaches. 

      Thanks,
      spencer graves

Peter Dalgaard wrote:

>"Subramanian Karthikeyan" <Subramanian_Karthikeyan at hc-sc.gc.ca> writes:
>
>  
>
>>My previous question put in a simpler  way:
>>
>>How would I pass a value of a variable to a function such as
>>
>>lm(Effect1~Trt*Dose, data = x, contrasts = list(Trt = contr.sum, Dose =
>>contr.sum))?
>>
>>Here, 'Effect' is a column name in my data matrix, and I want "Effect1" to
>>be replaced by "Effect2" and so on (my other column names in the data
>>frame) for successive anova calculations. So I am storing the column names
>>as an array, and passing the array as a parameter to the lm() function.
>>    
>>
>
>A canonical trick is
>
>for (myname in names(myframe)){
>  mycall <- substitute(lm(myvar~etc.etc.....),list(myvar=as.name(myname)))
>  myfit <- eval(mycall)
>  print(summary(myfit))
>}
>
>  
>