title: Pandas: Remove rows at random without shuffling dataset
body: <p>I've got a dataset which needs to omit a few rows whilst preserving the order of the rows. My idea was to use a mask with a random number between <code>0</code> and the length of my dataset but I'm not sure how to setup a mask without shuffling the rows around i.e. a method similar to sampling a dataset. </p>
  
  <p>Example: Dataset has 5 rows and 2 columns and I would like to remove a row at random.</p>
  
  <pre><code>Col1 | Col2
    A  |  1
    B  |  2 
    C  |  5     
    D  |  4
    E  |  0
  </code></pre>
  
  <p>transforms to:</p>
  
  <pre><code>Col1 | Col2
    A  |  1
    B  |  2   
    D  |  4
    E  |  0
  </code></pre>
  
  <p>with the third row (<code>Col1='C'</code>) omitted by a random choice.</p>
  
  <p>How should I go about this? </p>