title: Is pandas sort_values() deterministic in case of ties?
body: <p>I was wondering whether pandas sorting with <code>sort_values()</code> is a deterministic operation in case of ties, i.e. if calling <code>df.sort_values('foo')</code> would always return the same sorting, no matter how often I run it?
  One example would be</p>
  <pre><code>df=pd.DataFrame(np.random.randint(1, 3, 5),columns=[&quot;foo&quot;])
  df.sort_values(['foo'])
  
      foo
  0   1
  4   1
  1   2
  2   2
  3   2
  </code></pre>
  <p>I understand that the operation is not <a href="https://stackoverflow.com/questions/19580900/how-is-pandas-deciding-order-in-a-sort-when-there-is-a-tie">stable</a>, but is it deterministic?</p>