title: Splitting and collecting multi-word strings into numpy array
body: <p>I have an array <code>arr</code> of strings, each of which I would like to split by (' ') and then gather again into an array of words</p>
  <pre><code>import numpy as np
  arr = np.array(['foo bar baz', 'foo baz bar' 'bar foo baz'], dtype=object)
  </code></pre>
  <p>output should look something like:</p>
  <pre><code>array(['foo', 'bar', 'baz', 'foo', 'baz', 'bar', 'bar', 'foo', 'baz'])
  </code></pre>
  <p>Why does the following command throw an error and what is the correct method ?</p>
  <pre><code>np.char.split(arr, sep = ' ')
  
  TypeError: string operation on non-string array
  </code></pre>