title: string representation of a numpy array with commas separating its elements
body: <p>I have a numpy array, for example: </p>
  
  <pre><code>points = np.array([[-468.927,  -11.299,   76.271, -536.723],
                     [-429.379, -694.915, -214.689,  745.763],
                     [   0.,       0.,       0.,       0.   ]])
  </code></pre>
  
  <p>if I print it or turn it into a string with str() I get:</p>
  
  <pre><code>print w_points
  [[-468.927  -11.299   76.271 -536.723]
   [-429.379 -694.915 -214.689  745.763]
   [   0.       0.       0.       0.   ]]
  </code></pre>
  
  <p>I need to turn it into a string that prints with separating commas while keeping the 2D array structure, that is:</p>
  
  <pre><code>[[-468.927,  -11.299,   76.271, -536.723],
   [-429.379, -694.915, -214.689,  745.763],
   [   0.,       0.,       0.,       0.   ]]
  </code></pre>
  
  <p>Does anybody know an easy way of turning a numpy array to that form of string?</p>
  
  <p>I know that .tolist() adds the commas but the result loses the 2D structure.</p>