title: R data.frame ; get range of values in column
body: <p>I cannot figure out how to do this. I have a data.frame in R. It looks like this:</p>
  
  <pre><code>Scores &lt;- read.table(text = "
          ID Test1 Test2 Test3 Final
  1 Student1    20    23    21    48
  2 Student2    16    15    18    36
  3 Student3    25    20    22    40
  4 Student4    14    19    18    42
  5 Student5    10    15    14    30
  ")
  </code></pre>
  
  <p>What I want is to create a new data object that has the range of values for each test, including the final. So it will look something like this:</p>
  
  <pre><code>result &lt;- read.table(text = "
         min max
  Test1  10  25
  Test2  15  23
  Test3  14  22
  Final  30  48
  ")
  </code></pre>
  
  <p>It honestly doesn't matter to me whether it just lists the max and min values, or actually calculate the difference. I just can't figure out a way to implement this that isn't unnecessarily complicated. I know I can pull the columns out manually and individually, but there must be some better way of doing this. Something involving <code>by()</code> or <code>tapply()</code>? But I just cannot get them to work. </p>
  
  <p>Any ideas?</p>