title: Pandas Create DataFrame with two lists behaving differently
body: <p>I am trying to create a pandas data frame using two lists and the output is erroneous for a given length of the lists.(this is not due to varying lengths)</p>
  
  <p>Here I have two cases, one that works as expected and one that doesn't(commented out):</p>
  
  <pre><code>import string
  d = dict.fromkeys(string.ascii_lowercase, 0).keys()
  groups = sorted(d)[:3]
  numList = range(0,4)
  # groups = sorted(d)[:20]
  # numList = range(0,25)
  
  df = DataFrame({'Number':sorted(numList)*len(groups), 'Group':sorted(groups)*len(numList)})
  
  df.sort_values(['Group', 'Number'])
  </code></pre>
  
  <p>Expected Output: every item in groups, to correspond to all items in numList</p>
  
  <pre><code>  Group Number 
      a   0
      a   1
      a   2
      a   3
      b   0
      b   1
      b   2
      b   3
      c   0
      c   1
      c   2
      c   3
  </code></pre>
  
  <p>Actual Results: Works for case in which lists are sized 3 and 4 but not 20 , and 25 (I have commented out that case in the above code)</p>
  
  <p>Why is that? and how to fix that?</p>