title: How to apply stemming to a column in a pandas dataframe
body: <p>If i had the following dataframe:</p>
  <pre><code>import pandas as pd
  
  d = {'col1': ['goodness', 'beautiful'], 'col2': [3, 4]}
  df = pd.DataFrame(data=d)
  
  Output
          col1  col2
  0   goodness     3
  1  beautiful     4
  </code></pre>
  <p>I am using the porter stemmer:</p>
  <pre><code>print(porter.stem('goodness'))
  print(porter.stem('beautiful'))
  
  Output
  good
  beauti
  
  </code></pre>
  <p>How can I apply this stem function to all elements of col1 from the original dataframe?</p>
  <p>I have tried the following but no luck since it requires an input of word</p>
  <pre><code>df['col1'].apply(porter.stem(word), arg= word for word in df['col1'])
  </code></pre>
  <p>The desired output is:</p>
  <pre><code>        col1  col2
  0       good     3
  1       beauti     4
  </code></pre>