title: remove row if specific columns does not contain digit in pandas
body: <p>I have the following pandas dataframe:</p>
  <pre><code>&gt;&gt;&gt;ID      WKT
  0 4272   Point(4.21189  3.1298)
  1 2345   Point(None None)
  2 1254   Point (3.8945 4.6712)
  ...
  </code></pre>
  <p>I would like to remove rows that do no contain any digits in the 'WKT' column, like row 1.
  I saw that ther are functions as isnumeric() but I don't want to check if all the characters in the cell are digits, but only if it contains digits or nit, and if not to remove it.</p>
  <p>My desired output should look like this:</p>
  <pre><code>&gt;&gt;&gt;ID      WKT
  0 4272   Point(4.21189  3.1298)
  2 1254   Point (3.8945 4.6712)
  ...
  </code></pre>