8.19.5 Inverting the Y-axis

One good way of illustrate the usefulness of label callbacks in a slightly different context is to show how we can achieve the effect of an inverted Y-scale.

An inverted Y-scale has the lowest number at the top and the scale values increases downwards.

Even though JpGraph doesn't directly support this feature it is quite easy to achieve with just a few extra lines of code in your image script.

Before we continue we give an example of what we are referring to.

Figure 95: Inverted Y-axis [src] 

Two achieve this effect there are two simple steps to take:

1. Negate all you Y-value in the data
2. Create a callback that negates the scale labels so they appear to be positive.

And that's it! We refer you to the code in the example above for the details.