title: Combining results from a loop into a DataFrame
body: <p>Working with Python Pandas 0.19.1.</p>
  
  <p>I'm calling a function in loops, which returns a numeric list with length of 4 each time. What's the easiest way of concatenating them into a DataFrame?</p>
  
  <p>I'm doing this:</p>
  
  <pre><code>result = pd.DataFrame()
  for t in dates:
      result_t = do_some_stuff(t)
      result.append(result_t, ignore_index=True)
  </code></pre>
  
  <p>The problem is that it concatenates along the column instead of by rows.  If <code>dates</code> has a length of 250, it gives a single-column df with 1000 rows.  Instead, what I want is a 250 x 4 df.</p>