title: Why dataframe describe() method dosn't show all of the columns details after merge method?
body: <p>I have two csv file of datasets and I select some datas from first and marge them with the second dataset and replace to first one. so now I have new columns in my first datasets and now I need the average of one column what is new after marge. But when I use mean method or describe method they dosen't show that column details.</p>
  
  <pre><code>   dfgdp = pd.read_csv('../datasets/2014_world_gdp_with_codes.csv')
     dfgdp.rename(columns = {'GDP (BILLIONS)':'gdp', 'COUNTRY':'country'}, inplace = True)
     dfgdp = dfgdp[dfgdp['gdp']&gt;1000]
     dfgdp = pd.merge(dfgdp, dfmig, how='inner', on='country')
     dfgdp.describe()
  </code></pre>
  
  <p>That show the 4 columns but I have 8 columns in my table.</p>