title: How to check if the value is numeric?
body: <p>Can someone help me modify the function below to check if a number is numeric?</p>
  
  <pre><code># handy function that checks if something is numeric
  check.numeric &lt;- function(N){
    !length(grep("[^[:digit:]]", as.character(N)))
  }
  
  check.numeric(3243)
  #TRUE
  check.numeric("sdds")
  #FALSE
  check.numeric(3.14)
  #FALSE
  </code></pre>
  
  <p>I want <code>check.numeric()</code> to return <code>TRUE</code> when it's a decimal like 3.14.</p>