Understanding ggplot2's sec_axis() for Secondary Axes in R

This line of code is using the 'sec_axis()' function in R's ggplot2 package to create a secondary axis for plotting.

The 'sec_axis()' function takes two arguments: 'trans' and 'name'.

In this specific code, the 'trans' argument is '~rescale(.,c(0,0.5))'. This means that the values on the secondary axis will be transformed using the 'rescale()' function, which scales the values to a range between 0 and 0.5.

The 'name' argument is not specified in this code snippet, but it would typically be used to provide a label for the secondary axis.