Column order in pandas.concat
<p>I do as below:</p>

<pre><code>data1 = pd.DataFrame({ 'b' : [1, 1, 1], 'a' : [2, 2, 2]})
data2 = pd.DataFrame({ 'b' : [1, 1, 1], 'a' : [2, 2, 2]})
frames = [data1, data2]
data = pd.concat(frames)
data


   a    b
0   2   1
1   2   1
2   2   1
0   2   1
1   2   1
2   2   1
</code></pre>

<p>The data column order is in alphabet order. Why is it so?
and how to keep the original order?</p>