title: geom_abline multiple slopes and intercepts
body: <p>Considering this initial data frame (yld_sum):</p>
  
  <pre><code>  coef     pred      se    ci.lb    ci.ub    cr.lb    cr.ub Yld_class
     b0 3164.226 114.256 2940.289 3388.164 2142.724 4185.728      1Low
     b1  -20.698   3.511  -27.580  -13.816  -50.520    9.124      1Low
     b0 3985.287 133.220 3724.180 4246.394 2954.998 5015.576      2Low
     b1  -14.371   4.185  -22.573   -6.168  -44.525   15.784      2Low
  </code></pre>
  
  <p>How can I simplify my syntax to plot the two estimated regression lines with their respective CI, and obtain the following plot?</p>
  
  <p><a href="https://i.stack.imgur.com/4Bzti.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/4Bzti.png" alt="enter image description here"></a></p>
  
  <p>This is my verbose code:</p>
  
  <pre><code>library(tidyverse)
  
  yld_sum_est &lt;- yld_sum %&gt;% select(Yld_class, coef, pred) %&gt;% 
    spread(coef, pred)  
  
  yld_sum_low &lt;- yld_sum %&gt;% select(Yld_class, coef, ci.lb) %&gt;% 
    spread(coef, ci.lb)
  
  yld_sum_up &lt;- yld_sum %&gt;% select(Yld_class, coef, ci.ub) %&gt;% 
    spread(coef, ci.ub)
  
  ggplot() + 
    geom_abline(data = yld_sum_est, aes(intercept = b0, slope = b1)) +
    geom_abline(data = yld_sum_low, aes(intercept = b0, slope = b1), linetype= "dashed") +
    geom_abline(data = yld_sum_up, aes(intercept = b0, slope = b1), linetype= "dashed") +
    scale_x_continuous(limits=c(0,60), name="x") +
    scale_y_continuous(limits=c(1000, 4200), name="y") 
  </code></pre>