title: pandas: how to summarize unequal size datasets?
body: <p>Let's say I have datasets of <em>different size</em> eg <code>X_1 = [1,2,3]</code> and <code>X_2 = [4,5,6,7,8]</code>. I would like to create a dataframe with summary variables (mean, std, etc), with one dataset per row, and on statistic per column. How can I do that in pandas?</p>