title: Create inverse of each column in pandas dataframe and add prefix
body: <p>Sample dataframe:</p>
  
  <pre><code>df = pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6]})
  </code></pre>
  
  <p>I'd like to add inverses of each existing column to the dataframe and name them based on existing column names with a prefix, e.g. <code>inv_A</code> is an inverse of column <code>A</code> and so on.</p>
  
  <p>The resulting dataframe should look like so:</p>
  
  <pre><code>df_inv = pd.DataFrame({"A": [1, 2, 3], "B": [4, 5, 6], "inv_A": [1/1, 1/2, 1/3], "inv_B": [1/4, 1/5, 1/6]})
  </code></pre>
  
  <p>Obviously there are redundant methods like doing this in a loop, but there should exist much more pythonic ways of doing it and after searching for some time I didn't find anything. I understand that this is most probably a duplicate; if so, please point me to an existing answer.</p>