The TWODHIST macro makes a binned scatterplot, also known as a heat map or a two-dimensional histogram.This is effectively a scatterplot with squares plotted and shaded to reflect the count in each square.
It uses proc gmap to do this-- a more sophisticated and doubtless more flexible approach would use proc template and proc sgplot.
Use:
Parameters:
data Input data set
x variable to be plotted on the x-axis
y variable to be plotted on the y-axis
nbinsx number of categories to divide x into
nbinsy number of categories to divide y into
nshades number of levels of the count of the population in each square
The code has a number fo flaws and limitattions I know of, which are described within the code. Doubtless there are additional problems I know not of.
