title: extracting columns from dataframe with atleast three values above cutoff
body: <p>I am new to R  programming. Need help to filter my data.For example my data set is mtcars. I want to extract columns which have at least three values above 18. How do i do that.thanks</p>
  
  <p>I have used sort function but that is good only for one column each. not as a whole data frame.</p>