title: Convert values in a dataframe column when certain data type (pandas)
body: <p>I'm looking at a table of mock Yelp reviews (data_clean is my pandas.dataframe). My column 'stars' is mixed text and integers. I want to convert the text values to integers. I'm trying the below. It doesn't error but also doesn't work!</p>
  
  <pre><code>data_clean.stars.replace([type(data_clean.stars)=='string'],[data_clean['stars'].astype(int)])
  </code></pre>
  
  <p>Help appreciated!</p>