title: make a copy of a string column and cut the string based on certain value
body: <p>I have a DataFrame with a column with installation KKS-codes in Python.</p>
  <p>The KKS-codes look like this:</p>
  <blockquote>
  <p>1BLA43AA030
  1BOR53AR021
  1BHY28UI021</p>
  </blockquote>
  <p>I want to make a new column where the string only has the relevant information. sometimes the code requires a number but it usually doesn't. The required number is given after the 3digit letter which specify the certain object. like this:</p>
  <blockquote>
  <p>BLA
  BOR
  BHY2</p>
  </blockquote>
  <p>I cut the full KKS-codes  with</p>
  <pre><code>df_1['KKS'] = df_1.Object.str[1:4]
  </code></pre>
  <p>but for certain strings i need it to be</p>
  <pre><code>df_1['KKS'] = df_1.Object.str[1:5]
  </code></pre>
  <p>My if-statements don't work, please help</p>