为什么这个R函数抛出错误

Question

我试图在R中创建一个简单的包装函数。但它会引发错误并且我不明白为什么。

set.seed(98)
d1 <- data.frame(
          y = factor(rep(c("a","b","c","d"),25)), 
          a = rnorm(100), 
          b = rnorm(100)
)


mlog_reg_p = function(f, d, ...) {

    if(!(require("nnet"))) {
        stop("Package 'nnet' is not installed. install.packages('nnet')")
    }

    syx = match.call()
    su = summary(multinom(formula = f, data = d))
    z = su$coefficients / su$standard.errors

    p = (1 - pnorm(abs(z), 0, 1)) * 2

    list(
        syntax = syx,
        model_summary = su,
        p_values = p
    )
}

尝试运行时：

mlog_reg_p(y ~ a + b, d1)

它会抛出错误：

Error in stats::model.frame(formula = f, data = d): object 'f' not found

我搞砸了什么？