Perhaps something like this?
library(ggplot2)
df2 <- do.call(rbind, lapply(seq(nrow(df)), function(i)
data.frame(month = factor(month.abb[12:df$start.month[i]], levels = month.abb),
spec = df$spec[i])))
df2$spec <- factor(df2$spec, levels = names(rev(sort(table(df2$spec)))))
ggplot(df2, aes(month, spec, colour = spec)) +
geom_point(size = 8, shape = 15) +
coord_cartesian(ylim = c(1, 9)) +
labs(y = "Cumulative no. of specialties",
x = "Months",
colour = "Specialties") +
scale_color_manual(values = c("#ffc000", "#ed7d31", "#5a9bd5",
"#70ad46", "#44546b")) +
theme_classic() +
theme(axis.text.y.left = element_blank(),
axis.ticks.length.y = unit(0, "points"),
legend.background = element_rect(colour = "black"),
axis.text = element_text(size = 16),
axis.title = element_text(size = 16))
