title: How to append rows in a pandas dataframe in a for loop?
body: <p>I have the following for loop:</p>
  
  <pre><code>for i in links:
       data = urllib2.urlopen(str(i)).read()
       data = json.loads(data)
       data = pd.DataFrame(data.items())
       data = data.transpose()
       data.columns = data.iloc[0]
       data = data.drop(data.index[[0]])
  </code></pre>
  
  <p>Each dataframe so created has most columns in common with the others but not all of them. Moreover, they all have just one row. What I need to to is to add to the dataframe all the distinct columns and each row from each dataframe produced by the for loop</p>
  
  <p>I tried pandas concatenate or similar but nothing seemed to work. Any idea? Thanks.</p>