title: counting the number of values greater than 0 in R in multiple columns
body: <p>I have a dataset myDF in R with a the variables L1,L2,L3,L4. How can I get the number of observations in L2, L3, and L4 that area greater than 0?</p>
  
  <p>I would like to use the subset function, I'm just not sure how 
  Thanks! </p>
  
  <pre><code>L1     L2     L3    L4
  1       1     0     2
  2       1     4     1 
  3       1     3     1
  2       2     1     1
  </code></pre>
  
  <p>I would like to be able to create a function that would be able to tally up the number of rows in columns L2, L3, and L4 greater than 0. </p>