R 闪亮获取文件分隔符

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

很难说你在问什么，但听起来你试图在使用read.table加载文件后找出原始文件分隔符。

不幸的是，答案是否定的。

但是你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,zn1,2,3n4,5,6", 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