remove segments of lines in R

Question

I have these 3 lines:

line1 <- matrix(c(-1.81209, -1.80470, -1.80616, 55.68024, 55.67947,
                    55.67544), ncol=2)
line2 <- matrix(c(-1.80468, -1.80330, -1.79690, 55.68322, 55.68017,
                  55.67800), ncol=2)
line3 <- matrix(c(-1.79798, -1.80069, -1.78929, 55.68364, 55.68138,
                  55.67966), ncol=2)

line1L <- Line(line1)
line2L <- Line(line2)
line3L <- Line(line3)
my.lines <- Lines(list(line1L, line2L, line3L), ID="my.lines")
myLines <- SpatialLines(list(my.lines))

proj4string(myLines) <- CRS("+proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0")
myLinesSpatial <- spTransform(myLines, CRS("+init=epsg:27700 +datum=WGS84"))

plot(myLinesSpatial)

I need to discard any part of any line, that falls within 100m of any other line. This will result in segments of each of the three lines being removed. How can I do this?

Answer 1

This can be done with the rgeos package, e.g. with gBuffer and gDifference:

library("rgeos")
library("rgdal")

line1 <- matrix(c(-1.81209, -1.80470, -1.80616, 55.68024, 55.67947,
                    55.67544), ncol=2)
line2 <- matrix(c(-1.80468, -1.80330, -1.79690, 55.68322, 55.68017,
                  55.67800), ncol=2)
line3 <- matrix(c(-1.79798, -1.80069, -1.78929, 55.68364, 55.68138,
                  55.67966), ncol=2)

lines <- SpatialLines(list(Lines(list(Line(line1)), ID="1"),
                           Lines(list(Line(line2)), ID="2"),
                           Lines(list(Line(line3)), ID="3")))
l <- SpatialLinesDataFrame(lines, data=data.frame(ID=paste(1:3)))
proj4string(l) <- CRS("+proj=longlat +datum=WGS84 +ellps=WGS84 +towgs84=0,0,0")
lt <- spTransform(l, CRS("+init=epsg:27700 +datum=WGS84"))

plot(lt, lty=3)
buf_list <- vector(3, mode="list")
res <- vector(3, mode="list")
for (i in 1:3) {
  ind <- setdiff(1:3, i)
  buf_list[[i]] <- gBuffer(lt[ind,], width=200)
  res[[i]] <- gDifference(lt[i, ], buf_list[[i]])
}
lapply(buf_list, plot, col="#FFFFFF90", add=TRUE)
lapply(res, plot, col="red", lwd=2, add=TRUE)

Answer 2

iN ARCGIS buffer each line for the dataset and run each separately, take the separate shp outputs and combine into a single shp.