title: Python Remove brackets from arrays
body: <p>I have a list that contains many arrays.</p>
  
  <pre><code>coef
  
  [array([[1.72158862]]),
   array([[3.28338167]]),
   array([[3.28004542]]),
   array([[6.04194548]])]
  </code></pre>
  
  <p>Put it into dataframe gives:</p>
  
  <pre><code>azone = pd.DataFrame(
      {'zone': zone,
       'coef': coef
      })
  
      zone    coef
  0   1   [[1.7215886175218464]]
  1   2   [[3.283381665861124]]
  </code></pre>
  
  <p>I wonder if there are ways to remove brackets. I tried tolist() but not giving me a result.</p>
  
  <p>Also for another list:</p>
  
  <pre><code>value
  
  [[array([8.46565297e-294, 1.63877641e-002]),
   array([1.46912451e-220, 2.44570170e-003]),
   array([3.80589351e-227, 4.41242801e-004])]
  </code></pre>
  
  <p>I want to have only keep the second value. desire output is:</p>
  
  <pre><code>   value
  0  1.63877641e-002
  1  2.44570170e-003
  2  4.41242801e-004
  </code></pre>