title: Get column names from a matrix using a condition
body: <p>I'm new in R and trying to figure out the language.</p>
  
  <p>I have the following matrix:</p>
  
  <pre><code>               HRV Focus Tiguan Elantra
  Price      20265.0 18175  24995 17250.0
  Engine         1.8     1      2     1.8
  Auto           1.0     0      1     0.0
  Horsepower   141.0   123    200   145.0
  </code></pre>
  
  <p><strong>How can I get the column names from the cars that their price is bigger than 20000?</strong></p>
  
  <p>In the specific question the answer should be: HRV, Tiguan </p>
  
  <p>Thanks in advance!</p>