r 函数调用带有子集的 lm

Question

我正在编写一些代码，我发现了一些奇怪的东西。当我在某些面板数据的子集上运行 LM 时，它运行良好，如下所示:

library('plm')
data(Cigar)
lm(log(price) ~ log(pop) + log(ndi), data=Cigar, subset=Cigar$state==1)

Call:
lm(formula = log(price) ~ log(pop) + log(ndi), data = Cigar, 
subset = Cigar$state == 1)


Coefficients:
(Intercept)     log(pop)     log(ndi)  
  -26.4919       3.2749       0.4265  

但是当我尝试将其包装在一个函数中时，我得到:

myfunction <- function(formula, data, subset){
  return(lm(formula, data, subset))
}

myfunction(formula = log(price) ~ log(pop) + log(ndi), data = Cigar, subset = Cigar$state==1)

Error in xj[i] : invalid subscript type 'closure'

我真的不明白这里发生了什么，但它破坏了我编写的其他一些代码，所以我想知道。

Answer 1

问题似乎不在于子集。当我更改为 subset = (state == 1) 时，我从你的函数中得到了同样的错误。您的函数的参数未正确传递和评估。

我认为你最好使用 do.call

myfunction <- function(formula, data, subset) {
    do.call("lm", as.list(match.call()[-1]))
}

myfunction(log(price) ~ log(pop) + log(ndi), Cigar, state == 1)    
# Call:
# lm(formula = log(price) ~ log(pop) + log(ndi), data = Cigar, 
#     subset = state == 1)
#
# Coefficients:
# (Intercept)     log(pop)     log(ndi)  
#    -26.4919       3.2749       0.4265