Distance To Nearest Detector
Compute Euclidean distance from each of a set of points to the nearest detector in an array, or return the sequence number of the detector nearest each point.
distancetotrap(X, traps) nearesttrap(X, traps)
X |
coordinates |
traps |
traps object or 2-column matrix of coordinates |
distancetotrap returns the distance from each point in X to the
nearest detector in traps. It may be used to restrict the points
on a habitat mask.
For traps objects with polygon detector type (polygon, polygonX), and for SpatialPolygons, the function rgeos::gDistance is used internally if the package rgeos is available (from secr 4.2.0). The method is otherwise approximate and uses only the first polygon.
distancetotrap returns a vector of distances (assumed to be in metres).
nearesttrap returns the index of the nearest trap.
## restrict a habitat mask to points within 70 m of traps ## this is nearly equivalent to using make.mask with the ## `trapbuffer' option temptrap <- make.grid() tempmask <- make.mask(temptrap) d <- distancetotrap(tempmask, temptrap) tempmask <- subset(tempmask, d < 70)
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