title: R plot: how to make a histogram with horizontal lines using plot()
body: <p>How can I use <code>plot</code> to turn this plot sideways so the histogram bars are horizontal?</p>
  
  <pre><code>size&lt;- abs(rnorm(20,10,10))
  age&lt;-c(seq(1, 20, by=2))
  plot(size~age, type=("n")); lines(size~age, type=c("l"), lines(size~age, type=c("h")))
  </code></pre>
  
  <p><img src="https://i.stack.imgur.com/EckXI.png" alt="enter image description here"></p>
  
  <p>What I want is roughly something like this, with the histogram lines horizontal:</p>
  
  <p><img src="https://i.stack.imgur.com/Vc0Nh.png" alt="enter image description here"></p>
  
  <p>which I did with </p>
  
  <pre><code>plot(size~age, type=("n"), yaxt="n", xaxt="n", ylab=""); lines(size~age, type=c("l"), lines(size~age, type=c("h"))); axis(4); axis(1,las=2)
  </code></pre>
  
  <p>and then rotating the image output in other software. </p>
  
  <p>I'd like to know how I can use the <code>plot</code> function to get the output plot sideways so I can make groups of them in <code>R</code> without having to rotate them outside of <code>R</code>. </p>
  
  <p><strong>UPDATE</strong> Thanks to the very helpful suggestion from @csgillespie I've got this, which has got me on my way:</p>
  
  <pre><code>size&lt;- abs(rnorm(20,10,10)) 
  age&lt;-c(seq(1, 40, by=2)) # sorry for the typo in the first set of example data above
  plot(-age~size, type="n",yaxt="n", ylab="Age", xlab="Size")
  lines(-age~size)
  segments(0, -age, size, -age)
  axis(2, labels=c(seq(0,max(age), by=5)), at=-c(seq(0,max(age), by=5)), las=1) # this is a more general approach to labelling the axis ticks
  </code></pre>
  
  <p>and here's resulting plot (not pretty yet, but I think I can do the rest from here):</p>
  
  <p><img src="https://i.stack.imgur.com/6isNJ.png" alt="enter image description here"></p>