title: How to append a numpy array to a pandas dataframe
body: <p>I'm trying to append a 3x2 numpy array to an existing dataframe. Something like this:</p>
  
  <pre><code>import pandas as pd
  import numpy as np
  df = pd.Dataframe({"A": [0,0,0], "B": [1,1,1]})
  arr = np.arange(6).reshape(3, 2)
  
  df[["C", "D"]] = arr  # NOPE!
  </code></pre>
  
  <p>How do I get this to work?</p>