title: Extract plot line formula as vector
body: <p>I got data.frame like this:</p>
  
  <p><code>V1 V2
  -251 1426
  -250 1466
  -249 1546
  -248 1482
  -247 1509
  -246 1475</code>
  I built linear model like:</p>
  
  <pre><code>fit=lm(x1$V2~x1$V1)
  </code></pre>
  
  <p>Then i plot this line</p>
  
  <pre><code>lines(x1$V1,fitted(fit),col="red")
  </code></pre>
  
  <p>So, the question is:
  Is there any way to extract plotted line as data.frame or as formula f(x)=ax+b? Thanks in advance!
  PS Just curious.</p>