title: Pandas crosstab on DataFrame 1-dimension error
body: <p>I am trying to compute group frequencies using this multi-indexed DataFrame:</p>
  
  <pre><code>In [1]: frame
  Out[1]:
                      position      values
  idmajor  idminor
    22        2           6           A
     4        1           7           B
    11        1           7           C
    23        1           7           B
     1        1           8           C
              9           8           C
     4        1           8           C
              1           8           C
  </code></pre>
  
  <p>Here is my code and error:</p>
  
  <pre><code>In [2]: pd.crosstab(frame.position, frame.values)
  Out[2]: Exception: Data must be 1-dimensional
  </code></pre>
  
  <p>Here is what I am trying to output:</p>
  
  <pre><code>Out[2]:
     categories    A       B       C
     values
     6             1       0       0
     7             0       2       1
     8             0       0       4
  </code></pre>
  
  <p>I'm reading through <em>Python for Data Analysis</em> and have just started with the <code>pandas</code> library. I am struggling to find answers or examples that will give me a greater understanding to this problem. Any advice is greatly appreciated!</p>
  
  <p>EDIT: Due to the multi-index of the DataFrame I was misled by the Exception. The multi-index nature of this frame has nothing to do with the Exception.</p>