title: Pandas ignore non-numeric values
body: <p>I have this df:</p>
  
  <pre><code>     X
  0   13500
  1   13600
  2   BBOX-001
  3   Mobi-1
  4   15003
  5   15004
  </code></pre>
  
  <p>I am trying to enter a new column. if x >15000 then the value is A, otherwise B. If X is non-numeric (BBOX-001, Mobi-1), then it should display the value in column X:</p>
  
  <pre><code>     X        Y
  0   13500     B
  1   13600     B
  2   BBOX-001  BBOX-001
  3   Mobi-1    Mobi-1
  4   15003     A
  5   15004     A
  </code></pre>
  
  <p>I have this below but how do I ignore the non-numeric values in column X?</p>
  
  <pre><code>df['Y'] = np.where(df['X'] &gt; 15000, 'A', 'B')
  </code></pre>