title: Python Pandas concatenate a Series of strings into one string
body: <p>In python pandas, there is a Series/dataframe column of str values to combine into one long string:</p>
  
  <pre><code>df = pd.DataFrame({'text' : pd.Series(['Hello', 'world', '!'], index=['a', 'b', 'c'])})
  </code></pre>
  
  <p>Goal: 'Hello world !'</p>
  
  <p>Thus far methods such as <code>df['text'].apply(lambda x: ' '.join(x))</code> are only returning the Series. </p>
  
  <p>What is the best way to get to the goal concatenated string?</p>