title: In gam.plot (mgcv package in R) , I want to draw reference point and acceptable y axis
body: <p>I would like to make gam.plot with reference</p>
  
  <p>for example, if I can refer to age:70, y axis would reveal "odds ratio"  </p>
  
  <p>not like below</p>
  
  <p>With manual (<a href="https://cran.r-project.org/web/packages/mgcv/mgcv.pdf),I" rel="nofollow noreferrer">https://cran.r-project.org/web/packages/mgcv/mgcv.pdf),I</a> performed various tries in s() or plot() or gam()</p>
  
  <pre><code>set.seed(1)
  num &lt;- 1000
  age &lt;- runif(num,min=65,max=85)
  XX &lt;- data.frame(age)
  XX$death &lt;- rbinom(num,1,(XX$age-72)^2/169)
  head(XX)
  plot(mgcv::gam(death ~ s(age),data=XX))
  </code></pre>
  
  <p>reference is age:70 and y axis reveal "odds ratio"</p>