If your railroad is just a single line feature running approx N-S then: Create a box polygon for your study area, make sure the railroad just crosses it at N and S edges
Use rgeos functions overlaying the RR line with the box polygon to create the E and W polygons Job done? On Fri, Sep 16, 2011 at 1:11 PM, Mathieu Rajerison <mathieu.rajeri...@gmail.com> wrote: > Hi List, > > > I've got a railroad shapefile and a corine land cover raster. > > I'd like to perform a land cover comparative analysis between the west side > of the railroad and the right side. > > To do that, I tried first to have a raster with values=1 when on the east > and 0 when on the west. > But my calculation is very slow. > > Maybe anyone has a better idea on how to accomplish that? > > Here is the code, for the moment: > > #* *I create a raster of the same extent and resolution as the corine land > cover raster >> track.r <- raster(extent(clc.ov)) >> res(track.r) <- res(clc.ov) > > # I rasterize it >> track.r <- rasterize(track, track.r) > > # I extract the row-col pairs of cells with value 1 >> rowCol <- rowColFromCell(track.r, which(track.r[]==1)) > > # I give the value 1 to each cell which col number is > to that of the > rasterized line cell and of same row >> for (i in seq(1,length(rowCol))) { > track.r[rowCol[i,1], rowCol[i,2]:ncols] <- 1 > } > # too slow..... > > > Any help would be greatly appreciated, > > Mathieu > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-Geo mailing list > R-sig-Geo@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-geo > -- blog: http://geospaced.blogspot.com/ web: http://www.maths.lancs.ac.uk/~rowlings web: http://www.rowlingson.com/ twitter: http://twitter.com/geospacedman pics: http://www.flickr.com/photos/spacedman _______________________________________________ R-sig-Geo mailing list R-sig-Geo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-geo