title: delete rows which have a column content <0
body: <p>there is a dataframe with dataframe.shape = (1000, 10). </p>
  
  <pre><code>dataframe = dataframe.loc[data.column_A &lt;0].reset_index(drop=True) 
  </code></pre>
  
  <p>prints out the (50, 10) --> 50 rows which are smaller 0 in column_A. 
  But I need the full dataframe minus the 50 rows which have column_A content smaller 0. The end result should be dataframe.shape = (950, 10). </p>