title: concatenating, pandas, and join_axes
body: <p>I've been searching the web for an example of this, but haven't found anything.</p>
  
  <p>Let <code>df1, df2, .. dfn</code> be pandas dataframes, indentically indexed.</p>
  
  <p>What is happening when I run the command: </p>
  
  <p><code>pandas.concat([df1,..,dfn],axis=1,join_axes=[df1.index])</code></p>
  
  <p>It doesn't give me an error and provides a dataframe.  I've pasted all I could find in the documentation in relation to this.  What happens when there is a mismatch among the indices? How does pandas know to use the indexes of the other dataframes, I thought I might have to put all the indexes of the other <code>n-1</code> pandas dataframes.</p>
  
  <p>Any tips?</p>
  
  <p><strong>join_axes : list of Index objects
  Specific indexes to use for the other n - 1 axes instead of performing inner/outer set logic</strong></p>