title: Append multiple 1D arrays to an "empty" 2D array - Python
body: <p>Consinder the following example:</p>
  
  <pre><code># z = empty object, if possible empty 2D-array
    N = 2
  
  for i in range(N):
      l = i * array([2,2,2])
      # z.function(l)
  </code></pre>
  
  <p>Is there a function or a way to append multiple 1D-arrays to an empty object z and convert it into an 2D array </p>
  
  <p>In my case N = 10**5 and the l-arrays are computed.</p>
  
  <p>In the end i want a 2D array so i can apply slice operations (extract columns,rows,..)  </p>