SnowMap: Draw John Snow's Map of Cholera in London

Description

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

x location of the scale used by Sscale

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

John Mackenzie, "GIS Analyses of Dr. Snow's Map"", http://www1.udel.edu/johnmack/frec480/cholera/cholera2.html describes some related visualizations using ArcGIS.

Examples

Run this code

# NOT RUN {
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)

# }

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