title: Write dictionary with numpy arrays to .csv
body: <p>I want to write resultfiles to .csv. I prepared a simple test example.</p>
  <pre><code>import numpy as np
  data = {}
  testdata = np.array([1,2,3,4,5])
  
  data['set1'] = {'a': testdata, 'b': testdata, 'c': testdata}
  data['set2'] = {'a2': testdata, 'b2': testdata, 'c2': testdata}
  data['set3'] = {'a3': testdata, 'b3': testdata, 'c3': testdata}
  </code></pre>
  <p>It would be great to get a result file like this:</p>
  <p><a href="https://i.stack.imgur.com/yjJcU.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/yjJcU.jpg" alt="enter image description here" /></a></p>
  <p>Is there a simple way that you can recomment?</p>