title: Residuals from 1:1 line
body: <p>I want to measure the distance between a set of points and a 1:1 line. I can build a linear model and get the residuals from the best fit, but I cant get the measure from a 1:1 line. Any helpful hints? </p>
  
  <pre><code>#build a df of random numbers     
  x=runif(100, 0, 100)
      y=runif (100, 0, 100)
      df=cbind (x,y)
      df=as.data.frame(df)
  #build a linear model    
  lm1&lt;-lm(y~x, data=df)
      summary (lm1)
  #plot the data, lm best fit and 1:1 (red) line)    
      plot (y~x, data=df, pch=16)
      line (lm1)
      abline abline(0,1, col="red")
  #get residulas for the linear model 
  y.resid= resid (lm1)
  </code></pre>