You didn't parse the output you pasted in correctly: pt1.cpoly@polygons[[1]]@Polygons[[1]]@coords
or coordinates(pt1.cpoly@polygons[[1]]@Polygons[[1]]) > class(pt1.cpoly) [1] "SpatialPolygons" attr(,"package") [1] "sp" So see ?"SpatialPolygons-class" for details. Sarah On Wed, Apr 8, 2015 at 5:07 PM, Monica Pisica <[email protected]> wrote: > > Hi, > > > > I am struggling to extract the polygon vertices from a list of an object > class "Polygons", specifically the slot "coords". > > > > I have a point, and i "draw" a buffer around with gBuffer, i am "extracting" > the polygon form the SpatialPolygons class and i end up with a list of 1 one > object Polygons class that seems to have slots, but if i try to extract them > i get an error. > > > > So here it goes after i load the respective libraries: sp, maptools, rgdal, > rgeos > > pt1 <- data.frame(x=217680.2, y = 3817555) > > coordinates(pt1) <- c("x", "y") > > crs = "+proj=utm +zone=11 +datum=NAD83 +units=m +no_defs +ellps=GRS80 > +towgs84=0,0,0" > > > > proj4string(pt1) <- CRS(crs) > > pt1.cpoly <- gBuffer(pt1, width = 100, byid = TRUE) > > > > pt1.cpoly > > class : SpatialPolygons > > features : 1 > > extent : 217580.2, 217780.2, 3817455, 3817655 (xmin, xmax, ymin, ymax) > > coord. ref. : +proj=utm +zone=11 +datum=NAD83 +units=m +no_defs +ellps=GRS80 > +towgs84=0,0,0 > > > > pt1.poly <- pt1.cpoly@polygons > > > > pt1.poly > > [[1]] > > An object of class "Polygons" > > Slot "Polygons": > > [[1]] > > An object of class "Polygon" > > Slot "labpt": > > [1] 217680.2 3817554.7 > > > > Slot "area": > > [1] 30901.7 > > > > Slot "hole": > > [1] FALSE > > > > Slot "ringDir": > > [1] 1 > > > > Slot "coords": > > x y > > [1,] 217780.2 3817555 > > [2,] 217775.3 3817524 > > [3,] 217761.1 3817496 > > [4,] 217739.0 3817474 > > Etc. ….. > > > > pt1.crd <- pt1.poly[[1]]@coords > > Error: no slot of name "coords" for this object of class "Polygons" > > > > So my question is: How do i access the "coords" slot i clearly see when i > print pt1.poly on the screen? > > > > Thanks for any help, > > > > Monica > ______________________________________________ > [email protected] mailing list -- To UNSUBSCRIBE and more, see > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. -- Sarah Goslee http://www.functionaldiversity.org ______________________________________________ [email protected] mailing list -- To UNSUBSCRIBE and more, see https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
