title: filtering lines in a numpy array according to values in a range
body: <p>Let an array:</p>
  
  <pre><code> a =np.array([[1,2],[3,-5],[6,-15],[10,7]])
  </code></pre>
  
  <p>to get lines with elements of the second column above -6 it' s possible to do</p>
  
  <pre><code>&gt;&gt;&gt; a[a[:,1]&gt;-6]
  array([[ 1,  2],
     [ 3, -5],
     [10,  7]])
  </code></pre>
  
  <p>but how to get lines with the second element between -6;3?
  I tried:</p>
  
  <pre><code>&gt;&gt;&gt; a[3&gt;a[:,1]&gt;-6]
  </code></pre>
  
  <p>and also (which raises an error):</p>
  
  <pre><code>&gt;&gt;&gt; np.ma.masked_inside(a,-6,3)
  </code></pre>
  
  <p>which gives:</p>
  
  <pre><code> masked_array(data =
   [[-- --]
    [-- --]
    [6 -15]
    [10 7]],
           mask =
    [[ True  True]
    [ True  True]
    [False False]
    [False False]],
     fill_value = 999999)
  </code></pre>
  
  <p>but the result is not too clear</p>
  
  <p>Thanks
  jp</p>