title: Calculate sum, mean and variance for several columns of data in R
body: <p>I'm new to R. The professor asked us to obtain sum, mean and variance for several columns of data which are in Excel form. Now, I want to try to use R to solve them rather than enter the formula in Excel and drag. I have imported the data into R and they are correctly displayed. I can use the commands <code>sum ()</code> and <code>sd ()</code> and <code>var ()</code> for EACH column.</p>
  
  <p>My question is: is there a way to let R display the sum, sd, and variance for each column at the same time? (Rather than calculating these again and again for each column).</p>
  
  <p>I mean something like <code>colSum(col1, col2, col3,...)</code> and the line just shows the sum for each column.</p>