Duplicating pandas dataframe vertically
<p>I have the foll. dataframe:</p>

<pre><code>    Month  Day   season
0       4   15  current
1       4   16  current
2       4   17  current
3       4   18  current
4       4   19  current
5       4   20  current
</code></pre>

<p>I would like to duplicate it like so:</p>

<pre><code>    Month  Day   season
0       4   15  current
1       4   16  current
2       4   17  current
3       4   18  current
4       4   19  current
5       4   20  current
6       4   15  past
7       4   16  past
8       4   17  past
9       4   18  past
10       4   19  past
11       4   20  past
</code></pre>

<p>I can duplicate it using:</p>

<pre><code> df.append([df]*2,ignore_index=True)
</code></pre>

<p>However, how do I duplicate so that the <code>season</code> column has <code>past</code> as the duplicated values instead of <code>current</code></p>