#!Rscript
a <- c(1,2,3,4,5,4,3,2,1,5,6,-12)
b <- c(7,4,2,1,-1,-4,5,3,2,1,0,-11)
swappoints <- vector()
if (length(a) != length(b)) {
    print("Horribly sorry, old chap, we need equally sized lists for this to work")
    q()
}
a.is.greater <- F
if (a[[1]] > b[[1]]) a.is.greater <- T
for (i in c(1:length(b))) {
    if (a[[i]] > b[[i]] & a.is.greater == F) {
        a.is.greater <- T
        swappoints <- c(swappoints, a[[i]])
    }
    if (b[[i]] > a[[i]] & a.is.greater == T) {
        a.is.greater <- F
        swappoints <- c(swappoints, -1 * a[[i]])
    }
}
# segmented y
redToGreen = swappoints[swappoints < 0]
greenToRed = swappoints[swappoints > 0]
png('SpreadCurves2.png')
plot(seq_len(length(b)),b, xpd=NA, main='Contrived setup', type='l')
lines(b, col='red')
lines(a, col='blue')
polygon(seq_len(length(b))[swappoints>0], b[swappoints>0], col='green')
polygon(seq_len(length(b))[swappoints<0], b[swappoints<0], col='red')
dev.off()
print(paste('Output in SpreadCurves2.png in', getwd()))