Passing function argument to formula

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北荒
北荒 2021-01-16 05:24

I\'m trying to understand why

foo = function(d,y,x) {
    fit = with(d, lm(y ~ x))
}
foo(myData, Y, X)

won\'t work, where for instance

2条回答
  •  醉梦人生
    2021-01-16 06:08

    @DMT's answer explains what's going on nicely.

    Here are the hoops to jump through if you want things to work as you expect:

    lmwrap <- function(d,y,x) {
        ys <- deparse(substitute(y))
        xs <- deparse(substitute(x))
        f <- reformulate(xs,response=ys)
        return(lm(f,data=d))
    }
    mydata <- data.frame(X=1:10,Y=rnorm(10))
    lmwrap(mydata,Y, X)
    

    Or it can be simplified a bit if you pass the column names as strings rather than symbols.

    lmwrap <- function(d,y,x) {
        f <- reformulate(xs, response=ys)
        return(lm(f, data=d))
    }
    lmwrap(mydata, "Y", "X")
    

    This approach will be a bit fragile, e.g. if you pass arguments through another function. Also, getting the "Call" part of the formula to read Y~X takes more trickery ...

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