R语言，暂停循环并要求用户继续

Question

我有一个想法，在某些迭代中暂停循环并向“用户”询问一些答案。

例如

some_value = 0
some_criteria = 50
for(i in 1:100)
{
  some_value = some_value + i
  if(some_value > some_criteria)
  {
    #Here i need to inform the user that some_value reached some_criteria
    #I also need to ask the user whether s/he wants to continue operations until the loop ends
    #or even set new criteria
  }
}

再次，我想暂停循环，并询问用户是否要继续，例如：“按 Y/N”

Answer 1

some_value = 0
some_criteria = 50
continue = FALSE
for(i in 1:100){
  some_value = some_value + i
  print(some_value)
  if(some_value > some_criteria && continue == FALSE){
    #Here i need to infrom user, that some_value reached some_criteria
    print(paste('some_value reached', some_criteria))

    #I also need to ask user whether he wants co countinue operations until loop ends
    #or even set new criteria

    question1 <- readline("Would you like to proceed untill the loop ends? (Y/N)")
    if(regexpr(question1, 'y', ignore.case = TRUE) == 1){
      continue = TRUE
      next
    } else if (regexpr(question1, 'n', ignore.case = TRUE) == 1){
      question2 <- readline("Would you like to set another criteria? (Y/N)")
      if(regexpr(question2, 'y', ignore.case = TRUE) == 1){
        some_criteria <-  readline("Enter the new criteria:")
        continue = FALSE
      } else {
        break  
      }
    }
  }
}

Answer 2

对于此类事情使用弹出消息对话框通常会显得更明显且更用户友好。下面我使用 tcltk2 包中的

tkmessageBox

来实现此目的。在此示例中，一旦满足条件，我就使用

break

退出循环。根据您的具体用例，有时在这种情况下最好使用

while

循环，而不是过早地打破

for

循环。

library(tcltk2)
some_value = 0
some_criteria = 50
continue = TRUE
for(i in 1:100) { 
  some_value = some_value + i
  if(some_value > some_criteria) {
    response <- tkmessageBox(
      message = paste0('some_value > ', some_criteria, '. Continue?'), 
      icon="question", 
      type = "yesno", 
      default = "yes")
    if (as.character(response)[1]=="no") continue = FALSE
  }
  if (!continue) break()
}

Answer 3

如果您有多个 some_criteria 选项（就像我发现这个时所做的那样），请扩展 Paulo MiraMor 的回复

regexpr(question1, 'y', ignore.case = TRUE) == 1

可以替换为

question1 %in% list_of_criteria_conditions

其中 list_of_criteria_conditions 可以类似于

list_of_criteria_conditions <- c("criteria_1", 1, TRUE)