title: Python Pandas How to count number of rows that have at least one zero
body: <p>I have a data frame in pandas and would like to do some calculations from it.</p>
  
  <p>I think it's more like an intersection kind of problem</p>
  
  <p>Col 1 = [0, 1, 2, 0]
  Col 2 = [0, 0 ,1, 0]</p>
  
  <p>Above is my data frame and I would like to count numbers of rows that have at least one 0 in a column.
  For example, I expect the output to be 3 since there are 3 rows that have at least a 0.</p>