leglabs makes character strings from the same break points. This function was copied from the soon-to-be
deprecated maptools
package with permission from author Roger Bivand
leglabs(vec, under = "under", over = "over", between = "-", reverse = FALSE)
vector of break values
character value for under
character value for over
character value for between
flag to reverse order of values, you will also need to reorder colours, see example
Roger Bivand, Nick Bearman, Nicholas Lewin-Koh