title: Sum only negative numbers across columns in dataframe Pandas
body: <p>I would like to sum by only negative numbers across all the columns in a dataframe.</p>
  
  <p>I have seen this post: <a href="https://stackoverflow.com/questions/42063716/pandas-sum-up-multiple-columns-into-one-column">Pandas: sum up multiple columns into one column</a></p>
  
  <p>My data looks like this:</p>
  
  <p>But I would like to sum only the negative numbers. How do i do that?</p>