title: Calculating and creating percentage column from two columns
body: <p>I have a df (<code>Apple_farm</code>) and need to calculate a percentage based off values found in two of the columns (<code>Good_apples</code> and <code>Total_apples</code>) and then add the resulting values to a new column within Apple_farm called 'Perc_Good'.</p>
  
  <p>I have tried:</p>
  
  <pre><code>Apple_farm['Perc_Good'] = (Apple_farm['Good_apples'] / Apple_farm['Total_apples']) *100
  </code></pre>
  
  <p>However this results in this error:</p>
  
  <blockquote>
    <p>TypeError: unsupported operand type(s) for /: 'str' and 'str'</p>
  </blockquote>
  
  <p>Doing</p>
  
  <p><code>Print Apple_farm['Good_apples']</code>  and <code>Print Apple_farm['Total_apples']</code></p>
  
  <p>Yields a list with numerical values however dividing them seems to result in them being converted to strings?</p>
  
  <p>I have also tried to define a new function:</p>
  
  <pre><code>def percentage(amount, total):
      percent = amount/total*100
      return percent
  </code></pre>
  
  <p>but are unsure on how to use this.</p>
  
  <p>Any help would be appreciated as I am fairly new to Python and pandas!</p>