title: how to copy numpy array value into higher dimensions
body: <p>I have a (w,h) np array in 2d. I want to make a 3d dimension that has a value greater than 1 and copy its value over along the 3rd dimensions. I was hoping broadcast would do it but it can't. This is how i'm doing it</p>
  
  <pre><code>arr = np.expand_dims(arr, axis=2)
  arr = np.concatenate((arr,arr,arr), axis=2)
  </code></pre>
  
  <p>is there a a faster way to do so?</p>