title: How to find pandas columns with one or more negative values
body: <p>If I want find out all the features in a pandas dataframe with at least one zero value then I can use the following command.</p>
  <pre><code>df.isin([0]).sum()
  </code></pre>
  <p>That's simple and elegant. What's the equivalent of that to find out features with negative values.</p>
  <p>There seems to be no straightforward way to find out all the columns in a pandas dataframe with at least one negative value. Can you please help? Many thanks in advance.</p>