title: Is it possible to fix a center reference point while dynamically generating range in ggplot?
body: <p>I couldn't find any information on this topic so I am looking for some assistance. </p>
  
  <h2>Issue:</h2>
  
  <p>In ggplot it is easy to dynamically generate y axis upper and lower bounds with <code>scale_y_continuous</code>. However, dynamically generated bounds have their issues - especially when it comes to comparing data. Consider the instance where one would like to see a fixed range to make easy comparisons and not get misled by a visual with changing bounds. If I fix the ranges with the <code>scale_y_continuous(limits = c("lower bound", "upper bound"))</code> then I can run into issues with certain graphs not being visible for that fixed range. </p>
  
  <h2>Question:</h2>
  
  <p>Is it possible to fix a center/focal point in a ggplot while dynamically generating the upper and lower bounds. For example, let's say that a certain graph extends from -10,000 to 5,000 and a second graph extends from -6,000 to 12,000 - to make this visual comparison easy I would like the center point to be stationary. So when I am cycling back and forth between graphs there is a point of reference. </p>
  
  <p>Thus, I would like to fix a reference point of 0 to remain at the same center of the graphs while only extending the upper and lower bounds. </p>
  
  <h2>Clarification:</h2>
  
  <p>Picture a coordinate plane with the origin at 0. If I were to draw a graph of x^2 for x:[-2,2] y:[4,4] and also x:[0,4] y:[0, 16] in order to easily compare the plots I would like to see the same window for both graphs as opposed to the second graph being zoomed into the first quadrant (positive plane) of the coordinate plane. </p>
  
  <p>Is this possible? Any assistance would be much appreciated. </p>