splancs (version 2.01-9)

burkitt: Burkitt's lymphoma in Uganda

Description

Locations of cases of Burkitt's lymphoma in the Western Nile district of Uganda 1960-1975. The time variable is recorded as the number of days starting from an origin of 1 Jan 1960. The examples given below show how the chron() function and derived time structures may be used to analyse the data in the time dimension.

Usage

data(burkitt)

format

The data is provided as a data table: lll{ x numeric grid eastings y numeric grid northings t numeric day number starting at 1/1/1960 of onset age numeric age of child patient } as a points object burpts of burkitt$x and burkitt$y; and a point object of the area boundary burbdy.

source

Williams, E. H. et al. 1978, - Bailey and Gatrell 1995, ch. 3.

References

Bailey, T. C. and Gatrell, A. C. 1995, Interactive spatial data analysis. Longman, Harlow.

Examples

data(burkitt)
try.obj <- try(library(chron))
if (!is.na(match("chron", try.obj))) {
burdates <- chron(burkitt$t, out.format="y-m-d",
	origin=c(day=1, month=1, year=1960))
froms <- seq.dates(chron("7/1/1960", origin=c(1,1,1960)),
	chron("7/1/1975", origin=c(1,1,1960)), "years")
tos <- seq.dates(chron("9/30/1960", origin=c(1,1,1960)),
	chron("9/30/1975", origin=c(1,1,1960)), "years")
burd <- density(burdates, bw=100)
plot(chron(burd$x, origin=c(day=1, month=1, year=1960)), burd$y,
	type="n", xaxp=c(chron("1/1/1960", origin=c(1,1,1960)),
	chron("1/1/1976", origin=c(1,1,1960)),16), xlab="time",
ylab="density")
for (i in 1:length(tos)) polygon(c(froms[i], tos[i], tos[i], froms[i]),
	c(par("usr")[3], par("usr")[3], par("usr")[4], par("usr")[4]), 
	col="grey", border=NULL)
lines(chron(burd$x, origin=c(day=1, month=1, year=1960)), burd$y,
	lwd=3, col="red")
title("Density plot of Burkitt's lymphoma in West Nile district, 3Q grey shaded")
op <- par(mfrow=c(3,5))
for (i in 1961:1975) {
	polymap(burbdy)
	pointmap(burpts[which(years(burdates) == i),], add=TRUE, pch=19)
	title(i)
}
par(op)
op <- par(mfrow=c(2,2))
for (i in 1:4) {
	polymap(burbdy)
	pointmap(burpts[which(codes(quarters(burdates)) == i),], add=TRUE,
pch=19)
	title(paste(i, "Q", sep=""))
}
par(op)
op <- par(mfrow=c(3,4))
for (i in 1:12) {
	polymap(burbdy)
	pointmap(burpts[which(codes(months(burdates)) == i),], add=TRUE, pch=19)
	title(levels(months(burdates, FALSE))[i])
}
par(op)
}