title: python Regex returns matched string, but also returns blanks where it could not match
body: <p>This is my input string :</p>
  
  <pre><code>str = '32 -3.723 +98.6 .357 0.86'
  </code></pre>
  
  <p>And my regex is :</p>
  
  <pre><code>print re.findall('[+-]?\d*\.?\d*',str)
  </code></pre>
  
  <p>It returns :</p>
  
  <pre><code>['32', '', '-3.723', '', '+98.6', '', '.357', '', '0.86', '']
  </code></pre>
  
  <p>What I could not understand why all these empty strings in between. </p>