You could approach it as a minimum distance between points problem.
With sp, first convert each SpatialPolygons to SpatialLines, generate
regular points on each line and then compute minimum dist between all
points. Obviously, there is a trade off between the number of points
and precision.
Something like this:
require(sp)
# 1st "polygon"
p1 = SpatialLines(list(Lines(list(Line(cbind(c(10.92, 8.13, 17.12,
29.97, 31.06, 25.95, 20.21,10.92),
c(86.56, 73.24, 59.75, 67.54, 75.84, 86.39, 95.04,86.56) ))))))
# 2nd "polygon"
p2 = SpatialLines(list(Lines(list(Line(cbind(c(41.75, 35.55, 42.68,
53.99, 60.96, 58.94, 53.21,41.75),
c(66.5, 53.87, 41.07, 42.11, 51.62, 64.77, 67.36,66.5)))))))
plot(1:100, type = "n")
plot(p1, add = T)
plot(p2, add = T)
# regular sampling on each polygon
n = 500
p1.pts = spsample(p1, n = n, type = "regular")
p2.pts = spsample(p2, n = n, type = "regular")
# minimun distance between polygons' edges
min(apply(coordinates(p1.pts), 1, function(p)
spDistsN1(coordinates(p2.pts), p )))
...
Mihai
Marion TAFANI wrote:
dear all,
we want to calculate the minimun distance between polygons' edges , do
you know any package or function which can help us ? we try to work
with vectors rather than raster but we lack some tools. we only found
how to calculate distances between centroids but nothing between edges.
thanks
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