R: Burkitt's lymphoma in Uganda

burkitt {splancs} | R Documentation

## 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:

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
dates | factor | day as string yy-mm-dd

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)
    burDates <- as.Date(as.character(burkitt$dates), "%y-%m-%d")
    res <- aggregate(rep(1, length(burDates)), list(quarters(burDates), format(burDates, "%y")), sum)
    plot(as.numeric(as.character(res$Group.2)) +
     0.25*(as.numeric(substr(as.character(res$Group.1), 2, 2))-1),
     res$x, type="h", lwd=3, col=ifelse(as.character(res$Group.1)=="Q3",
     "grey","red"), xlab="year", ylab="count", xaxt="n")
    axis(1, at=seq(61,75,4), labels=format(seq.Date(as.Date("1961/1/1"),
     as.Date("1975/1/1"), "4 years")))
    title("Plot of Burkitt's lymphoma in West Nile district,\nQ3 grey shaded")
    op <- par(mfrow=c(3,5))
    for (i in unique(format(burDates, "%y"))) {
    	polymap(burbdy)
    	pointmap(burpts[which(format(burDates, "%y") == i),], add=TRUE, pch=19)
    	title(main=paste("19", i, sep=""))
    }
    par(op)
    op <- par(mfrow=c(2,2))
    for (i in c("Q1", "Q2", "Q3", "Q4")) {
    	polymap(burbdy)
    	pointmap(burpts[which(unclass(quarters(burDates)) == i),], add=TRUE,
    pch=19)
    	title(main=i)
    }
    par(op)
    op <- par(mfrow=c(3,4))
    for (i in months(seq(as.Date("70-01-01", "%y-%m-%d"), len=12, by="1 month"))) {
    	polymap(burbdy)
    	pointmap(burpts[which(unclass(months(burDates)) == i),], add=TRUE, pch=19)
    	title(main=i)
    }
    par(op)

[Package splancs version 2.01-43 Index]