Description Usage Format Details References
Locations of devils claw in a farming paddock. Locations to all weeds are given as x,y coordinates and are contained in one of eight 150m wide transects (75m each side). The weeds seen by observers are specified as Seen=1.
1 |
A data frame with 742 observations on the following 5 variables.
label
label of the transect 1 to 8
x
x coordinate along horizontal (east-west) of 1200m x 1200m paddock
y
y coordinate along vertical (north-south) of 1200m x 1200m paddock
distance
absolute perpendicular distance from line
Seen
weed was seen if 1 and 0 if missed
The data provided from Melville and Welsh did not have the y-coordinate. We have constructed
y-coordinates by drawing randomly from a uniform distribution in the y-direction such that no two weeds are at
the exact same location. The code used to create weeds.all
was as follows:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 | data(weeds)
# Fudge the data ever so slightly to appease spatstat so the transects don't abut
# and all points are contained within the strips.
weeds$SignedDistance[weeds$SignedDistance==75]=74.99
weeds$SignedDistance[weeds$SignedDistance==-75]=-74.99
weeds.all=data.frame(label=weeds$Transect, x=(weeds$Transect-1)*150+75
+weeds$SignedDistance, y=floor(runif(dim(weeds)[1])*1200),
distance=weeds$Distance, Seen=weeds$Seen)
while(any(duplicated(data.frame(x=weeds.all$x,y=weeds.all$y))))
{
npts=sum(as.numeric(any(duplicated(data.frame(x=weeds.all$x,y=weeds.all$y)))))
weeds.all$y[duplicated(data.frame(x=weeds.all$x,y=weeds.all$y))]=
runif(npts)*1200
}
save(weeds.all,file="weeds.all.rda")
|
See weeds
for more details.
Melville, G. J., and A. H. Welsh. 2001. Line transect sampling in small regions. Biometrics 57:1130-1137.
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