我想在特定时间运行R代码里面(I want to run a R code at a specifi

我想运行在一个特定的时间，我需要一个R代​​码里面。 而且过程结束后，我要终止R对话。

如果代码是如下，

tm<-Sys.time()
write.table(tm,file='OUT.TXT', sep='\t');
quit(save = "no")

我应该怎么做才能运行在“2012-04-18 17时25分40秒”这个代码。 我需要你的帮助。 提前致谢。

Answer 1:

这是最容易使用的任务计划程序的Windows，或cron作业 Linux下。 在那里，你可以指定要在您指定的特定时间运行的命令或程序。 我绝对不会推荐的R脚本，如：

time_to_run = as.POSIXct("2012-04-18 17:25:40")
while(TRUE) {
   Sys.sleep(1)
   if(Sys.time == time_to_run) {
     ## run some code
   }
}

Answer 2:

如果不知为何，你不能使用cron作业服务，并有R内安排，下列R-代码演示如何等待特定的时间量，以便在预先指定的目标时间来执行。

stop.date.time.1 <- as.POSIXct("2012-12-20 13:45:00 EST") # time of last afternoon execution. 
stop.date.time.2 <- as.POSIXct("2012-12-20 7:45:00 EST") # time of last morning execution.
NOW <- Sys.time()                                        # the current time
lapse.time <- 24 * 60 * 60              # A day's worth of time in Seconds
all.exec.times.1 <- seq(stop.date.time.1, NOW, -lapse.time) # all of afternoon execution times. 
all.exec.times.2 <- seq(stop.date.time.2, NOW, -lapse.time) # all of morning execution times. 
all.exec.times <- sort(c(all.exec.times.1, all.exec.times.2)) # combine all times and sort from recent to future
cat("To execute your code at the following times:\n"); print(all.exec.times)

for (i in seq(length(all.exec.times))) {   # for each target time in the sequence
  ## How long do I have to wait for the next execution from Now.
  wait.time <- difftime(Sys.time(), all.exec.times[i], units="secs") # calc difference in seconds.
  cat("Waiting for", wait.time, "seconds before next execution\n")
  if (wait.time > 0) {
    Sys.sleep(wait.time)   # Wait from Now until the target time arrives (for "wait.time" seconds)
    {
      ## Put your execution code or function call here
    }
  }
}

文章来源: I want to run a R code at a specific time