title: Pythonic method of pulling multiple arrays out of a dictionary and stacking them with numpy
body: <p>I have a dictionary that has arrays in them. I'd like to grab those arrays out with numpy and stack them using np.dstack and I cannot figure how.
  The dictionary format is shown below minus the nxx of course. Additionally, I'm showing the nx numbers in a sequence, and while the dictionary contains a keys n1, n2 up to the highest nvalue, they are not actually in a sequence.</p>
  
  <pre><code>{'n0': masked_array, 'n1': masked_array, 'n2': masked_array, ..., 'nxx': masked_array}
  </code></pre>
  
  <p>The data for each pair is displayed as</p>
  
  <pre><code>'n0': masked_array(
    data=[[0.13530391454696655, 0.26814308762550354, 0.26814308762550354,
           ..., --, --, --],
          [0.21222707629203796, 0.22386012971401215, 0.19620446860790253,
           ..., --, --, --],
          [0.22701908648014069, 0.23818181455135345, 0.23777709901332855,
           ..., --, --, --],
          ...,
          [--, --, --, ..., --, --, --],
          [--, --, --, ..., --, --, --],
          [--, --, --, ..., --, --, --]],
    mask=[[False, False, False, ...,  True,  True,  True],
          [False, False, False, ...,  True,  True,  True],
          [False, False, False, ...,  True,  True,  True],
          ...,
          [ True,  True,  True, ...,  True,  True,  True],
          [ True,  True,  True, ...,  True,  True,  True],
          [ True,  True,  True, ...,  True,  True,  True]],
    fill_value=-inf,
    dtype=float32)
  </code></pre>
  
  <p>Specifying the a print of each entity using</p>
  
  <pre><code>print(arraydict['n0'])
  </code></pre>
  
  <p>provides</p>
  
  <pre><code>[[0.13530391454696655 0.26814308762550354 0.26814308762550354 ... -- --
    --]
   [0.21222707629203796 0.22386012971401215 0.19620446860790253 ... -- --
    --]
   [0.22701908648014069 0.23818181455135345 0.23777709901332855 ... -- --
    --]
   ...
   [-- -- -- ... -- -- --]
   [-- -- -- ... -- -- --]
   [-- -- -- ... -- -- --]]
  </code></pre>
  
  <p>So if they were individual variables I'd be able to do something like (following the n order is important)</p>
  
  <pre><code>arraystack = np.dstack((n0, n1, n2, n3, ..., nxx, ))
  </code></pre>
  
  <p>I cannot for the life of me conceptualize how to use np.dstack to pull and stack each from the dictionary starting with n0 onwards as</p>
  
  <pre><code>arraystack = np.dstack(([arraydict[key] for key in arraydict]))
  </code></pre>
  
  <p>does seems to work, but it does not seem to maintain the n0, n1, n2, n3 sequence.</p>