title: 45 degree line in Plot function in R
body: <p>I have data like this : </p>
  
  <pre><code>df &lt;- data.frame(X=rnorm(10,0,1), Y=rnorm(10,0,1), Z=rnorm(10,0,1))
  </code></pre>
  
  <p>I need to plot each variables against each other, so I used </p>
  
  <pre><code>plot(df)
  </code></pre>
  
  <p>It plotted each variable within the df against the each other exactly what is required. </p>
  
  <p>But I want to add 45 degree line(where x=y), in each and every sub plot. I want to know how it can be done ? I also tried  through loop but due to "space constraint" it could not happen[in reality i have 5 variables within the df]. Please help.</p>
  
  <p>Thanks</p>