"ppp"representing the point pattern of cell locations. Entries include
xCartesian $x$-coordinate of cell
yCartesian $y$-coordinate of cell
marksfactor with levels
onindicating ``off'' and ``on'' cells } See
ppp.objectfor details of the format.
The true dimensions of the rectangle are 1060 by 662 microns. The coordinates here are scaled to a rectangle of height 1 and width $1060/662 = 1.601$ so the unit of measurement is approximately 662 microns.
The data were analysed by Diggle (1986).