title: How to concat multiple Dataframes
body: <p>The <code>result</code> dataframe should be the combined version of three other dataframes: <code>dfa</code>, <code>dfb</code> and <code>dfc</code> and it should be:</p>
  
  <pre><code>     a     b    c
  0  1.0   0.0    0
  1    0  10.0    0
  2    0     0  100
  </code></pre>
  
  <p>Unfortunately the code below produces a different result:</p>
  
  <pre><code>result = pd.DataFrame()
  dfa = pd.DataFrame({'a':[1]})
  dfb = pd.DataFrame({'b':[10]})
  dfc = pd.DataFrame({'c':[100]})
  
  for df in [dfa, dfb, dfc]:
      result = result.reindex(columns=df.columns, fill_value=0)
      result = pd.concat([result, df], ignore_index=True)
  
  print result 
  </code></pre>
  
  <p>Here is what the results is:</p>
  
  <pre><code>     c
  0    0
  1    0
  2  100
  </code></pre>
  
  <p>What could be done to get the <code>result</code> needed?</p>