Question

对于简单的引导示例，我有以下代码。

X <- runif(100)
errors <- rexp(length(X))-1
Y <- 1 + 2*X + errors
ols.mod <- lm(Y ~ X)
boot <- Boot(ols.mod, method = "case", R = 1000)

如果以单独的行执行，则上面的代码有效。但是，当我将代码包装在如下函数中时：

test_func <- function() {
  X <- runif(100)
  errors <- rexp(length(X))-1
  Y <- 1 + 2*X + errors
  ols.mod <- lm(Y ~ X)
  boot <- Boot(ols.mod, method = "case", R = 1000)
}
test_func()

执行此操作将产生如下错误：

Error in eval(predvars, data, env): object 'Y' not found

关于为什么发生这种情况的任何想法？谢谢！

Answer 1

这对我有用。

doBootstrapping <- function(n = 100, r = 1000) {
  xy <- data.frame(X = runif(n = n))
  errors <- rexp(length(xy$X))-1
  xy$Y <- 1 + 2*xy$X + errors
  ols.mod <- lm(Y ~ X, data = xy)
  boot <- Boot(ols.mod, method = "case", R = r)
}

out <- doBootstrapping(n = 100, r = 1000)

> str(out)
List of 11
 $ t0       : Named num [1:2] 0.986 1.953
  ..- attr(*, "names")= chr [1:2] "(Intercept)" "X"
 $ t        : num [1:1000, 1:2] 1.188 1.073 1.083 1.127 0.964 ...
  ..- attr(*, "dimnames")=List of 2
  .. ..$ : NULL
  .. ..$ : chr [1:2] "(Intercept)" "X"
 $ R        : num 1000
 $ data     :'data.frame':  100 obs. of  1 variable:
  ..$ .zero: int [1:100] 0 0 0 0 0 0 0 0 0 0 ...
 $ seed     : int [1:626] 403 334 599478801 441938554 -1355732193 -409499586 -248637084 -2048103023 20568410 1088692573 ...
 $ statistic:function (data, indices, .fn)  
 $ sim      : chr "ordinary"
 $ call     : language boot::boot(data = dd, statistic = boot.f, R = R, .fn = f, parallel = parallel_env,      ncpus = ncores)
 $ stype    : chr "i"
 $ strata   : num [1:100] 1 1 1 1 1 1 1 1 1 1 ...
 $ weights  : num [1:100] 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 ...
 - attr(*, "class")= chr "boot"
 - attr(*, "boot_type")= chr "boot"

R引导函数包裹在函数中时产生错误

1 个答案: