title: How to add multiple lines using ggplot given two vectors of their coefficients without using for loop?
body: <p>Using for loop is significantly slower and just doesn't seems right. I would greatly appreciate it if someone could use some other method with geom_abline(intercept, slope).
  The variable Coeff is a list contains four data frames of all the parameters, each data frame have 1001 rows (the first one is useless).</p>
  
  <pre><code>p &lt;- qplot(x,y,data = data,color = I("blue"))
  for (i in 1:1000){
  p &lt;- p + geom_abline(intercept = Coeff[[1]]$Intercept[i+1], slope = Coeff[[1]]$X[i+1],alpha = 0.1,size = 0.1, colour = "red")
  }
  for (i in 1:1000){
  p &lt;- p + geom_abline(intercept = Coeff[[3]]$Intercept[i+1], slope = Coeff[[3]]$X[i+1],alpha = 0.1,size = 0.1, colour = "yellow")
  }
  </code></pre>