The data come from an investigation of a 924 ft x 924 ft (19.6 acre) plot in Lansing Woods, Clinton County, Michigan USA by D.J. Gerrard. The data give the locations of 2251 trees and their botanical classification (into hickories, maples, red oaks, white oaks, black oaks and miscellaneous trees). The original plot size (924 x 924 feet) has been rescaled to the unit square.
"ppp"representing the point pattern of tree locations. Entries include
xCartesian $x$-coordinate of tree
yCartesian $y$-coordinate of tree
marksfactor with levels indicating species of each tree } The levels of
ppp.objectfor details of the format of a point pattern object.
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