title: How can I subset a dataframe in a way that the rows in the new subset will have ordered numbers?
body: <p>I have a <code>df</code>:</p>
  <pre><code>df = data.frame(a = c(1, 2, 3), b = c(3, 2, 1))
  </code></pre>
  <p>I subset the <code>df</code> like so:</p>
  <pre><code>df = df[2:3, ]
  </code></pre>
  <p>Now, when I check <code>df</code> as follows:</p>
  <pre><code>&gt; df
  
    a b
  2 2 2
  3 3 1
  </code></pre>
  <p>the first value has a number 2, and the second number has a number 3. How can I subset the original <code>df</code> in a way that the new subset will have ordered numbers?</p>
  <p>Desired output:</p>
  <pre><code>&gt; df
  
    a b
  1 2 2
  2 3 1
  </code></pre>