Hi Sarah,
Thank you so much. This is exactly what i need it. I was wondering if my parsing was totally wrong. I read the SpatialPolygons-class help, but obviously i didn't understand it. Again, thanks so much, Monica ---------------------------------------- > Date: Wed, 8 Apr 2015 20:42:56 -0400 > Subject: Re: [R] extracting slot "coords" from a Polygons class object > From: sarah.gos...@gmail.com > To: pisican...@hotmail.com > CC: r-help@r-project.org > > 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 <pisican...@hotmail.com> 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 >> ______________________________________________ >> R-help@r-project.org 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 ______________________________________________ R-help@r-project.org 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.