Draw John Snow's Map of Cholera in London

The main function SnowMap draws versions of John Snow's map of cholera deaths in the South London area surrounding the Borad Street pump. during the 1854 outbreak.

It is a wrapper for the various subfunctions also listed here:
Splot sets up the basic plot
Sstreets draws the streets
Sdeaths plots the deaths
Sdeaths plots the pump locations
Sscale draws the scale
Spolygons draws the boundaries of the Voronoi polygons separating the pumps
Sdensity draws and fills contours of the 2D density of deaths

Usage

SnowMap(xlim = c(3, 20), ylim = c(3, 20), 
        axis.labels = FALSE, main = "Snow's Cholera Map of London", 
        scale = TRUE, polygons = FALSE, density=FALSE,
        streets.args = list(col = "grey", lwd = 1), 
        deaths.args = list(col = "red", pch = 15, cex = 0.6), 
        pumps.args = list(col = "blue", pch = 17, cex = 1.5, cex.lab = 0.9), 
        scale.args = list(xs = 3.5, ys = 19.7), 
        polygons.args = list(col=NA, border="brown", lwd=2, lty=1),
        density.args=list(bandwidth=c(0.5,0.5), 
                  col1=rgb(0,1,0,0),
                  col2=rgb(1,0,0,.8))
)

Splot(xlim = c(3, 20), ylim = c(3, 20), 
      xlab = "", ylab = "", 
      axis.labels = FALSE, 
      main = "Snow's Cholera Map of London")

Sdeaths(col = "red", pch = 15, cex = 0.6)

Spumps(col = "blue", pch = 17, cex = 1.5, cex.lab = 0.9)

Sstreets(col = "gray", lwd = 1)

Sscale(xs = 3.5, ys = 19.7)

Spolygons(col=NA, border="brown", lwd=2, lty=1)

Sdensity(bandwidth = c(0.5, 0.5), col1 = rgb(0, 1, 0, 0), col2 = rgb(1, 0, 0, 0.8))

Arguments

xlim: Limit for the horizontal axis. Specify ranges smaller than the defaults to zoom the plot.
ylim: Limit for the vertical axis.
axis.labels: Logical. Show axis tick mark labels?
main: Plot title
scale: Logical; draw a scale (in meters) on the plot
polygons: Logical; Use Spolygons to draw the Snow.polygons on the plot?
density: Logical; Use Sdensity to draw the 2D bivariate density of deaths on the plot?
streets.args: List of arguments passed to Sstreets
deaths.args: List of arguments passed to Sdeaths
pumps.args: List of arguments passed to Spumps
scale.args: List of arguments passed to Sscale
polygons.args: List of arguments passed to Spolygons. Note that col here now refers to the fill colors, passed to polygon. The col argument here can be a vector of up to 13 colors, one for each pump region.
density.args: List of arguments passed to Sdensity
xlab: Label for horizontal axis
ylab: Label for vertical axis
col: Color of points and lines used by various functions
pch: Point character used by by various functions
cex: Character size used by by various functions
cex.lab: Character size for labels used by Spumps
lwd: Line width used by by various functions
border: Color of border lines used by Spolygons
xs: x location of the scale used by Sscale
ys: y location of the scale used by Sscale
lty: Line type used by by various functions
bandwidth: Bandwidth used by bkde2D in Sdensity
col1: Lower level of color range used by colorRampPalette in Sdensity
col2: Upper level of color range used by colorRampPalette in Sdensity

Value

None

References

Snow, J. (1885). On the Mode of Communication of Cholera. London: John Churchill

Thomas Coleman, "John Snow Research project", https://www.hilerun.org/econ/papers/snow/index.html gives extensive analyses of Snow's data with R notebooks on Github.

Author

Michael Friendly

Examples

SnowMap()

SnowMap(axis.labels=TRUE)

SnowMap(deaths.args=list(col="darkgreen"))


SnowMap(polygons=TRUE, main="Snow's Cholera Map with Pump Polygons")


SnowMap(density=TRUE)