Returns the image object to show the heat map of years between the inputted set of vertices

data(sbGeneal)
varieties=c("Bedford", "Calland", "Narow", "Pella", "Tokyo", "Young", "Zane")
p = plotYearMatrix(varieties,sbGeneal,"Variety", "Variety", "Degree")
p + ggplot2::scale_fill_continuous(low="white", high="darkgreen")