title: How can I merge 2 column in python
body: <p>Suppose that I have define one 2x2 matrix using numpy:</p>
  
  <pre><code>array([[1, 2],
         [2, 3]]) 
  </code></pre>
  
  <p>Now the other 2x1 matrix: </p>
  
  <pre><code>array([[3],
         [4]])
  </code></pre>
  
  <p>How can I concatenate these 2 matrix by column, so that it will become:</p>
  
  <pre><code>array([[1, 2, 3],
         [2, 3, 4]])
  </code></pre>
  
  <p>And how can I also delete the specify column, so that it will became</p>
  
  <pre><code>array([[1],
         [2]])
  </code></pre>