title: Concatenating numpy arrays vertically and horizontally
body: <p>I have a numpy multidimensional array array with the following format:</p>
  
  <pre><code>a  = [[1,2],
        [8,9]]
  </code></pre>
  
  <p>Then I want to add a list with 3 values (e.g. <code>[4,5,6]</code> at the end horizontally and vertically with the following result:</p>
  
  <pre><code>a = [[1,2,4],
       [8,9,5],
       [4,5,6]]
  </code></pre>
  
  <p>Do I need to combine row_stack and column_stack somehow?</p>