title: how to use non-standard evaluation in R
body: <p>I want to use the variable name in a for loop but failed. I thought the problem is on the Non-Standard Evaluation in R.</p>
  <p>I tried the method on this website: <a href="https://stackoverflow.com/questions/49044806/standard-evaluation-and-non-standard-evaluation-in-r">Standard evaluation and non-standard evaluation in R</a>.</p>
  <pre><code>library(pROC)
  library(tidyverse)
  roc1 &lt;- aSAH %&gt;% roc(outcome, s100b)
  
  plot(roc1)
  
  a = 'roc1'
  
  # method from Stack overflow
  plot(!!rlang::sym(a))
  
  # Some other attempts
  plot(sym(a))
  
  plot(!sym(a))
  
  plot(!!sym(a))
  </code></pre>
  <p>Any help will be highly appreciated!!</p>