I am trying to extract coordinates from numerous polygons, originally contained in a SpatialPolygons object:
Sr1 = Polygon(cbind(c(2,4,4,1,2),c(2,3,5,4,2)))
Sr2 = Polygon(cbind(c(5,4,2,5),c(2,3,2,2)))
Srs1 = Polygons(list(Sr1), "s1")
Srs2 = Polygons(list(Sr2), "s2")
SpP = SpatialPolygons(list(Srs1,Srs2), 1:2)
I am trying to extract the coordinates from Sr1 and Sr2 from the SpP object. I saw this code elsewhere on stack exchange:
Coords<-SpP@polygons[[2]]@Polygons[[1]]@coords
I cannot understand the mismatch of the indexes in the square brackets, nevertheless it runs. But the output does not match the coordinates which I specified in Sr1 or Sr2. I have tried all the combinations of the indexes and cannot get the answer I am looking for!
Are you sure? They look the same (only posting as an "answer" since it's too long for a comment):
library(sp)
Sr1 <- Polygon(cbind(c(2, 4, 4, 1, 2), c(2, 3, 5, 4, 2)))
Sr2 <- Polygon(cbind(c(5, 4, 2, 5), c(2, 3, 2, 2)))
Srs1 <- Polygons(list(Sr1), "s1")
Srs2 <- Polygons(list(Sr2), "s2")
SpP <- SpatialPolygons(list(Srs1, Srs2), 1:2)
SpP@polygons[[1]]@Polygons[[1]]@coords
## [,1] [,2]
## [1,] 2 2
## [2,] 1 4
## [3,] 4 5
## [4,] 4 3
## [5,] 2 2
Sr1@coords
## [,1] [,2]
## [1,] 2 2
## [2,] 4 3
## [3,] 4 5
## [4,] 1 4
## [5,] 2 2
SpP@polygons[[2]]@Polygons[[1]]@coords
## [,1] [,2]
## [1,] 5 2
## [2,] 2 2
## [3,] 4 3
## [4,] 5 2
Sr2@coords
## [,1] [,2]
## [1,] 5 2
## [2,] 4 3
## [3,] 2 2
## [4,] 5 2