updateusr method for better barplot with lines/points

When using barplot with add y2 axis for lines or points by par(new=TRUE)  as show in the example code usually get shifted.

The updateusr method from Greg Snow's TeachingDemos package is a great solution for this problem. The idea behind updateusr is define new plot region according to the ratio of one unit in each axis.

The code:


Example code:(add space 8/20)


Result:

Axis scaling algorithm

A good look axes scale usually increase by 10^(x) or 0.5*10^(x) according to the data's range. Dorothy E. Pugh provide an algorithm (and SAS Macro) for generated suitable axis scale, I modified the SAS code into R code


reference:Dorothy E. Pugh(SUGI25), "A Robust Generalized Axis-scaling Macro"