covidChangePlot

resp <- httr::GET("https://api.coronavirus.data.gov.uk/v2/data?areaType=nation&metric=newTestsByPublishDate&metric=newCasesByPublishDate&format=json")
text <- httr::content(resp, as="text")
json <- jsonlite::fromJSON(text)
stats <- json$body %>% tibble::as_tibble()

to_plot <- stats %>% 
  mutate(date = as.Date(date)) %>% 
  filter(date >= "2020-09-01") %>% 
  group_by(areaName) %>% 
  arrange(date) %>% 
  mutate(
    daily_test = newTestsByPublishDate,
    daily_cases = newCasesByPublishDate,
    daily_rate =  100 * daily_cases / daily_test,
    sevenDayChange = daily_rate - lag(daily_rate, 7)
  ) 

ggplot(to_plot) + geom_smooth(aes(date, sevenDayChange, color=areaName)) + geom_hline(yintercept=0) + facet_wrap(~areaName)