Answer by cranberry for Plot two graphs in a same plot

Rather than keeping the values to be plotted in an array, store them in a matrix. By default the entire matrix will be treated as one data set. However if you add the same number of modifiers to the plot, e.g. the col(), as you have rows in the matrix, R will figure out that each row should be treated independently. For example:

x = matrix( c(21,50,80,41), nrow=2 )y = matrix( c(1,2,1,2), nrow=2 )plot(x, y, col("red","blue")

This should work unless your data sets are of differing sizes.