Applying gsub to tweak the syntax of a customized function-CodePudding

I have a (long) customized function and am wondering if there's a way to apply gsub to tweak the syntax for that function.

As an illustration, my original customized function looks like:

mymodel <- function(dataname){
  m <- lm(DV ~ IV, data = dataname)
  [a bunch of other lines to plot the results]
}

And I'd like to create another customized function like:

mymodel2 <- function(dataname){
  m <- lm(DV ~ IV   COVARIATE, data = dataname)
  [same lines as in mymodel syntax to plot the results]
}

Ideally I'm thinking of a solution like:

mysyntax <- '
  m <- lm(DV ~ IV, data = datname)
  [other lines to plot the results]
'

mysyntax2 <- gsub('DV ~ IV', 'DV ~ IV   COVARIATE', mysyntax) 
# this will keep all the other lines identical to mysyntax, other than the model specification

and then inputting this to create my customized function:

mymodel <- function(datname){mysyntax}
mymodel2 <- function(datname){mysyntax2}

I might be missing something very obvious, but I can't seem to find a way to pass a vector (mysyntax or mysyntax2) as an argument to a function.

Any help would be greatly appreciated!

CodePudding user response：

Suggest just defining a basic function mymodel_ with wrappers:

mymodel_ <- function(dataname, formula){
  m <- lm(formula, data = dataname)
}

mymodel1 <- function(dataname, formula = DV ~ IV) mymodel_(dataname, formula)
mymodel2 <- function(dataname, formula = DV ~ IV   COVARIATE) mymodel_(dataname, formula)

1a) or define a factory function that creates other functions

mymodelFactory <- function(formula) {
  function(dataname) {
    m <- lm(formula, data = dataname)
  }
}

mymodel1 <- mymodelFactory(DV ~ IV)
mymodel2 <- mymodelFactory(DV ~ IV   COVARIATE)

2) Although I don't really recommend this you can modify the mymodel function shown in the Note at the end like this:

mymodel3 <- mymodel 
body(mymodel3)[[2]][[3]][[2]] <- DV ~ IV   COVARIATE
mymodel3

3) This is not really recommended either but it can also be done using strings

s <- sub("DV ~ IV", "DV ~ IV   COVARIATE", format(mymodel))
mymodel4 <- eval(parse(text = s))
mymodel4

Note

mymodel <- function(dataname) {
  m <- lm(DV ~ IV, data = dataname)
}