R：如何使用ifelse语句的字符向量 [英] R: How to use ifelse statement for a vector of characters

问题描述

我正在尝试使用R来解决一个问题，但我的代码无法正常工作。我尝试调试，但似乎ifelse语句无法在某些数字上工作，这些数字似乎很随机。

这是测验： http://puzzles.nigelcoldwell.co.uk/six.htm

{pre> switch < - rep（off，100）
for（i in 1：100）{
k < - c（seq（i， 100，i））
ifelse（switches [k] ==off，switches [k]< - on，switches [k] < - off）
}


当我运行这段代码时，我会打开14，22，26，30，34等在那里我应该有关闭。

解决方案

ifelse 语法应该是

 开关<  -  rep（off，100）
 for（i in 1：100）{
k < -  seq（i，100，i）
 switches [k] } 
  

I am trying to solve a quiz using R, but my code does not work properly. I tried debugging, but it seems that the ifelse statement fails to work at certain numbers that seem pretty random.

Here is the quiz: http://puzzles.nigelcoldwell.co.uk/six.htm

switches <- rep("off", 100)
for(i in 1:100){
  k <- c(seq(i, 100, i))
  ifelse(switches[k] == "off", switches[k] <- "on", switches[k] <- "off")
}

When I run this code, I get "on" for 14, 22, 26, 30, 34, etc in which I should have got "off." Is there a mistake in the way I applied ifelse statement to a vector with vectorized index?

解决方案

The ifelse syntax should be

switches <- rep("off", 100)
for(i in 1:100){
  k <-  seq(i, 100, i)
  switches[k] <- ifelse(switches[k] == "off",  "on", "off")
}

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