exportPattern("^[[:alpha:]]+")
importFrom("grDevices", "colorRampPalette")
importFrom("graphics", "axis", "image", "layout", "lines", "par",
               "polygon", "text")
importFrom("stats", "as.formula", "contr.poly", "df.residual",
               "na.omit", "pt", "vcov")
importFrom("utils", "tail")
importFrom(magrittr,"%>%")
importFrom("ggplot2","aes","theme")