title: How to calculate means and std at once in pandas?
body: <p>For example, we have data like :</p>
  
  <pre><code>&gt;&gt;&gt; df
     name  score  times
  0   tom    100      1
  1   tom     99      2
  2   tom    100      3
  3  jack     99      1
  4  jack     99      2
  5  tony    100      1
  6  tony    100      2
  7  tony    100      3
  </code></pre>
  
  <p>I want to get a result like </p>
  
  <pre><code>   name       score std
  0  jack   99.000000  0
  1   tom   99.666667  0.57
  2  tony  100.000000  0
  </code></pre>
  
  <p>Is it possible to get the result at once?
  Now I have to calculate them seperately and combine the result</p>