title: Cannot extract number from string in python with split() method
body: <p>I looked online and every method for extracting numbers from strings uses the 
  <code>[int(word) for word in a_string.split() if word.isdigit()]</code>  method, 
  however when I run the code below, it does not extract the number <code>45</code></p>
  
  <pre><code>test = "ON45"
  print(test)
  print([int(i) for i in test.split() if i.isdigit()])
  </code></pre>
  
  <p>This is what python prints</p>
  
  <pre><code>ON45
  []
  </code></pre>
  
  <p>The second list is empty, it should be <code>[45]</code> which I should be able to access as integer using <code>output_int = test[0]</code></p>