title: generate conditional column in pandas
body: <p>I have:</p>
  <pre><code>pd.DataFrame({'price':['45p','£1.35']})
  </code></pre>
  <p>I want to convert these to numeric, and get:</p>
  <pre><code>pd.DataFrame({'price':['45p','£1.35'],'numeric':[0.45,1.35]})
  </code></pre>
  <p>I tried:</p>
  <pre><code>df['numeric']=np.where(df.price.str.contains('p') is True,
                    pd.to_numeric(df.price.str.replace('p',''))/100,
                   pd.to_numeric(df.price.str.replace('£','')))
  </code></pre>
  <p>and got the following error: <code>ValueError: Unable to parse string &quot;£1.35&quot; at position 7</code></p>
  <p>Any suggestions what I am doing wrong?</p>