R闪亮的获取文件分隔符

Question

加载后是否可以知道文件分隔符？？

我需要让文件分隔符在 read.table 等选项中使用它。 read.table(filename, encoding="UTF-8", stringsAsFactors=FALSE,header=TRUE, fill=TRUE,sep=XXXX)

Answer 1

很难说出您在问什么，但听起来您在使用 read.table 加载文件后试图找出原始文件分隔符。

很遗憾，答案是“不”。

但是您可以编写一个包装函数，在事后（尝试）捕获此信息：

read_table_capture_args <- function(...) {
  # capture unevaluated arguments
  outer_call <- match.call(expand.dots = FALSE)
  dots <- outer_call$...

  # pass those arguments to read.table() and save the result
  inner_call <- as.call(c(as.name("read.table"), dots))
  result <- eval(inner_call)

  # update the captured arguments with the implied default arguments
  all_args <- formals(read.table)
  implicit_argnames <- setdiff(names(all_args), names(dots))
  for (argname in implicit_argnames) {
      inner_call[[argname]] <- all_args[[argname]]
  }

  # return the result with an attribute "call" that contains all of the
  # arguments, explicit and implicit, used to produce the result
  structure(result, call = inner_call)
}

然后您可以使用它来恢复 sep 参数，如下所示：

# load your data as usual
my_data <- read_table_capture_args(text = "x,y,z\n1,2,3\n4,5,6", header = TRUE, sep = ",")
# get the unevaluated call that was used to load your data
my_data_call <- attr(my_data, "call")
# get the value of sep that was passed
my_data_sep <- my_data_call$sep