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Я пытаюсь создать график, который использует сюжетные функции и соединяет линии. Это будет сколько угодно строк. Я хочу запрашивать аргументы до тех пор, пока на входе не будет «нет». Пример:

 R:"Enter slope, intercept"
User:*input*
R:"Enter slope, intercept"
User:*input*
R:"Enter slope, intercept"
User:"no"
R:"Thank you for inputs"
  

затем появляется график

 myfunc <- function() {
  slopes <- intercepts <- numeric(0)
  while (TRUE) {
    user <- tolower(readline("Enter 'slope,intercept': "))
    if (trimws(user) == "no") {
      break
    }
    if (!nzchar(user)) {
      warning("Don't get short with me, I asked you a question ... or type 'no' to exit", call. = FALSE)
      next
    }
    parsed <- tryCatch(
      unlist(lapply(strsplit(user, ",")[[1]], as.numeric)),
      warning = function(w) w, error = function(e) e)
    if (inherits(parsed, c("error","warning"))) {
      warning("That made no sense to me ('", conditionMessage(parsed),
              "'), please try again", call. = FALSE)
      next
    }
    if (length(parsed) != 2L) {
      warning("I did not see (exactly) two values there, please try again", call. = FALSE)
      next
    }
    if (anyNA(parsed) || !is.numeric(parsed)) {
      warning("I see two things but at least one is non-numeric, please try again", call. = FALSE)
      next
    }
    slopes <- c(slopes, parsed[[1]])
    intercepts <- c(intercepts, parsed[[2]])
    lims <- range(c(0, intercepts))
    plot(NA, type = "n", xlim = lims, ylim = lims)
    ign <- mapply(abline, intercepts, slopes)
  }
  message("Thank you for your inputs, have a nice day")
}
  

Выполнение:

 myfunc()
# Enter 'slope,intercept': 
2,3
# Enter 'slope,intercept': 
3,2
# Enter 'slope,intercept': 
2.3
# Warning: I did not see (exactly) two values there, please try again
# Enter 'slope,intercept': 
2,abc
# Warning: That made no sense to me ('NAs introduced by coercion'), please try again
# Enter 'slope,intercept': 
2,3,4
# Warning: I did not see (exactly) two values there, please try again
# Enter 'slope,intercept': 
no
# Thank you for your inputs, have a nice day
  

Вам нужно подумать, как вы хотите установить ограничения x / y, в настоящее время это наивно и, вероятно, недостаточно.