title: R Difference with previous column across multiple columns
body: <p>I have a dataframe like this that resulted from a cumsum of variables:</p>
  
  <pre><code>id v1  v2   v3
  1  4   5    9   
  2  1   1    4
  </code></pre>
  
  <p>I I would like to get the difference among columns, such as the dataframe is transformed as:</p>
  
  <pre><code>id v1  v2   v3
  1  4   1    4   
  2  1   0    3
  </code></pre>
  
  <p>So effectively "de-acumulating" the resulting values getting the difference. This is a small example original df is around 150 columns.</p>
  
  <p>Thx!</p>