library(dslabs)
library(tidyverse)
data(us_contagious_diseases)
the_disease <- "Measles"
min_weeks_reporting <- 10
dat <- us_contagious_diseases %>%
  filter(
    disease == the_disease &
      weeks_reporting >= min_weeks_reporting &
      !is.na(population)
  ) %>%
  mutate(rate = count / population * 10000 * 52 / weeks_reporting)
dat %>% ggplot(aes(year, state, fill = rate)) +
  geom_tile(color="grey40")+
  scale_x_continuous(expand=c(0,0)) +
  scale_fill_gradientn(colors = RColorBrewer::brewer.pal(9, "Reds"), trans = "sqrt") +
  geom_vline(xintercept=1963, col = "blue") +
  theme_minimal() +
  theme(panel.grid = element_blank()) +
  ggtitle(the_disease) +
  ylab("") +
  xlab("")