6.2 John Snow’s cholera project

library(tidyverse)

library(HistData)
# ?HistData
SnowMap()

data("Snow.deaths")
Snow.deaths%>%
  ggplot(aes(x,y))+
  geom_point()

data("Snow.deaths")
data("Snow.streets")

plot(Snow.deaths[,c("x","y")], 
     col="red", pch=19, cex=.7)

slist <- split(Snow.streets[,c("x","y")],
               as.factor(Snow.streets[,"street"]))
?invisible
invisible(lapply(slist, lines, col="black"))