title: Count Data Frame Rows On Conditon for Arbitrary Columns in R
body: <p>I have a data frame with many columns.  I need to get a list for arbitrary columns and the number of rows that meet some conditions based on those columns.  For example, data frame has column a, b and c, I need to get row counts that b > 0 for b, and c > 0 for c in the form of</p>
  
  <p>column count</p>
  
  <p>b      23</p>
  
  <p>c      12</p>
  
  <p>What is the easiest way?</p>