R_Extracting coordinates from SpatialPolygonsDataFrame
Is it only me who have the problem with extracting coordinates of a polygon from SpatialPolygonsDataFrame object? I am able to extract other slots of the object (ID,plotOrder) but not coordinates (coords). I don't know what I am doing wrong. Please find below my R session where bdryData being the SpatialPolygonsDataFrame object with two polygons.
> bdryData
An object of class "SpatialPolygonsDataFrame"
Slot "data":
ID GRIDCODE
0 1 0
1 2 0
Slot "polygons":
[[1]]
An object of class "Polygons"
Slot "Polygons":
[[1]]
An object of class "Polygon"
Slot "labpt":
[1] 415499.1 432781.7
Slot "area":
[1] 0.6846572
Slot "hole":
[1] FALSE
Slot "ringDir":
[1] 1
Slot "coords":
[,1] [,2]
[1,] 415499.6 432781.2
[2,] 415498.4 432781.5
[3,] 415499.3 432782.4
[4,] 415499.6 432781.2
Slot "plotOrder":
[1] 1
Slot "labpt":
[1] 415499.1 432781.7
Slot "ID":
[1] "0"
Slot "area":
[1] 0.6846572
[[2]]
An object of class "Polygons"
Slot "Polygons":
[[1]]
An object of class "Polygon"
Slot "labpt":
[1] 415587.3 432779.4
Slot "area":
[1] 20712.98
Slot "hole":
[1] FALSE
Slot "ringDir":
[1] 1
Slot "coords":
[,1] [,2]
[1,] 415499.6 432781.2
[2,] 415505.0 432781.8
[3,] 415506.5 432792.6
[4,] 415508.9 432792.8
[5,] 415515.0 432791.5
[6,] 415517.7 432795.6
[7,] 415528.6 432797.7
[8,] 415538.8 432804.2
[9,] 415543.2 432805.8
[10,] 415545.1 432803.6
[11,] 415547.1 432804.7
[12,] 415551.7 432805.8
[13,] 415557.5 432812.3
[14,] 415564.2 432817.1
[15,] 415568.5 432823.9
[16,] 415571.0 432826.8
[17,] 415573.2 432828.7
[18,] 415574.1 432829.7
[19,] 415576.2 432830.7
[20,] 415580.2 432833.8
[21,] 415589.6 432836.0
[22,] 415593.1 432841.0
[23,] 415592.2 432843.7
[24,] 415590.6 432846.6
[25,] 415589.0 432853.3
[26,] 415584.8 432855.3
[27,] 415579.7 432859.8
[28,] 415577.7 432866.2
[29,] 415575.6 432868.1
[30,] 415566.7 432880.7
[31,] 415562.7 432887.5
[32,] 415559.2 432889.1
[33,] 415561.5 432890.7
[34,] 415586.2 432889.7
[35,] 415587.1 432888.6
[36,] 415588.5 432890.2
[37,] 415598.2 432888.7
[38,] 415599.1 432887.7
[39,] 415601.2 432886.7
[40,] 415603.1 432885.7
[41,] 415605.2 432884.7
[42,] 415606.1 432882.7
[43,] 415607.2 432880.7
[44,] 415608.3 432878.3
[45,] 415612.2 432874.8
[46,] 415614.7 432871.9
[47,] 415617.1 432870.7
[48,] 415622.4 432868.2
[49,] 415622.0 432862.4
[50,] 415624.2 432855.4
[51,] 415633.2 432845.3
[52,] 415639.0 432841.1
[53,] 415642.8 432832.9
[54,] 415647.5 432828.7
[55,] 415654.3 432820.3
[56,] 415654.1 432816.5
[57,] 415658.2 432812.8
[58,] 415661.9 432808.6
[59,] 415663.5 432808.7
[60,] 415668.1 432803.5
[61,] 415676.5 432801.3
[62,] 415679.1 432802.7
[63,] 415680.1 432802.7
[64,] 415681.1 432802.7
[65,] 415682.2 432802.7
[66,] 415685.8 432804.7
[67,] 415691.8 432802.2
[68,] 415693.6 432798.9
[69,] 415696.2 432777.0
[70,] 415689.8 432773.5
[71,] 415683.7 432771.6
[72,] 415680.2 432766.7
[73,] 415679.0 432765.6
[74,] 415676.8 432753.7
[75,] 415671.4 432747.7
[76,] 415662.7 432747.2
[77,] 415658.7 432750.0
[78,] 415657.0 432746.3
[79,] 415654.1 432743.7
[80,] 415652.3 432739.8
[81,] 415649.6 432739.6
[82,] 415648.0 432739.7
[83,] 415641.9 432736.4
[84,] 415633.4 432736.9
[85,] 415630.2 432734.7
[86,] 415622.3 432733.6
[87,] 415614.4 432726.5
[88,] 415617.1 432719.1
[89,] 415612.5 432718.1
[90,] 415610.0 432720.9
[91,] 415606.2 432716.6
[92,] 415603.2 432713.9
[93,] 415601.4 432710.0
[94,] 415580.3 432708.7
[95,] 415545.1 432709.7
[96,] 415543.5 432711.5
[97,] 415534.0 432715.7
[98,] 415527.1 432713.7
[99,] 415521.1 432711.6
[100,] 415505.6 432710.6
[101,] 415501.3 432710.9
[102,] 415499.3 432708.7
[103,] 415495.6 432711.6
[104,] 415482.6 432726.2
[105,] 415477.2 432734.0
[106,] 415478.1 432737.7
[107,] 415479.2 432739.7
[108,] 415480.9 432743.4
[109,] 415486.5 432751.2
[110,] 415493.2 432760.7
[111,] 415494.1 432762.7
[112,] 415498.1 432767.9
[113,] 415497.2 432770.7
[114,] 415490.6 432773.2
[115,] 415493.2 432775.6
[116,] 415496.0 432778.7
[117,] 415499.2 432779.7
[118,] 415499.6 432781.2
Slot "plotOrder":
[1] 1
Slot "labpt":
[1] 415587.3 432779.4
Slot "ID":
[1] "1"
Slot "area":
[1] 20712.98
Slot "plotOrder":
[1] 2 1
Slot "bbox":
min max
x 415477.2 415696.2
y 432708.7 432890.7
Slot "proj4string":
CRS arguments:
+proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000
+datum=OSGB36 +units=m +no_defs +ellps=airy
+towgs84=446.448,-125.157,542.060,0.1502,0.2470,0.8421,-20.4894
Subsetting second polygon from bdryData
> bdryData@polygons[[2]]
An object of class "Polygons"
Slot "Polygons":
[[1]]
An object of class "Polygon"
Slot "labpt":
[1] 415587.3 432779.4
Slot "area":
[1] 20712.98
Slot "hole":
[1] FALSE
Slot "ringDir":
[1] 1
Slot "coords":
[,1] [,2]
[1,] 415499.6 432781.2
[2,] 415505.0 432781.8
[3,] 415506.5 432792.6
[4,] 415508.9 432792.8
[5,] 415515.0 432791.5
[6,] 415517.7 432795.6
[7,] 415528.6 432797.7
[8,] 415538.8 432804.2
[9,] 415543.2 432805.8
[10,] 415545.1 432803.6
[11,] 415547.1 432804.7
[12,] 415551.7 432805.8
[13,] 415557.5 432812.3
[14,] 415564.2 432817.1
[15,] 415568.5 432823.9
[16,] 415571.0 432826.8
[17,] 415573.2 432828.7
[18,] 415574.1 432829.7
[19,] 415576.2 432830.7
[20,] 415580.2 432833.8
[21,] 415589.6 432836.0
[22,] 415593.1 432841.0
[23,] 415592.2 432843.7
[24,] 415590.6 432846.6
[25,] 415589.0 432853.3
[26,] 415584.8 432855.3
[27,] 415579.7 432859.8
[28,] 415577.7 432866.2
[29,] 415575.6 432868.1
[30,] 415566.7 432880.7
[31,] 415562.7 432887.5
[32,] 415559.2 432889.1
[33,] 415561.5 432890.7
[34,] 415586.2 432889.7
[35,] 415587.1 432888.6
[36,] 415588.5 432890.2
[37,] 415598.2 432888.7
[38,] 415599.1 432887.7
[39,] 415601.2 432886.7
[40,] 415603.1 432885.7
[41,] 415605.2 432884.7
[42,] 415606.1 432882.7
[43,] 415607.2 432880.7
[44,] 415608.3 432878.3
[45,] 415612.2 432874.8
[46,] 415614.7 432871.9
[47,] 415617.1 432870.7
[48,] 415622.4 432868.2
[49,] 415622.0 432862.4
[50,] 415624.2 432855.4
[51,] 415633.2 432845.3
[52,] 415639.0 432841.1
[53,] 415642.8 432832.9
[54,] 415647.5 432828.7
[55,] 415654.3 432820.3
[56,] 415654.1 432816.5
[57,] 415658.2 432812.8
[58,] 415661.9 432808.6
[59,] 415663.5 432808.7
[60,] 415668.1 432803.5
[61,] 415676.5 432801.3
[62,] 415679.1 432802.7
[63,] 415680.1 432802.7
[64,] 415681.1 432802.7
[65,] 415682.2 432802.7
[66,] 415685.8 432804.7
[67,] 415691.8 432802.2
[68,] 415693.6 432798.9
[69,] 415696.2 432777.0
[70,] 415689.8 432773.5
[71,] 415683.7 432771.6
[72,] 415680.2 432766.7
[73,] 415679.0 432765.6
[74,] 415676.8 432753.7
[75,] 415671.4 432747.7
[76,] 415662.7 432747.2
[77,] 415658.7 432750.0
[78,] 415657.0 432746.3
[79,] 415654.1 432743.7
[80,] 415652.3 432739.8
[81,] 415649.6 432739.6
[82,] 415648.0 432739.7
[83,] 415641.9 432736.4
[84,] 415633.4 432736.9
[85,] 415630.2 432734.7
[86,] 415622.3 432733.6
[87,] 415614.4 432726.5
[88,] 415617.1 432719.1
[89,] 415612.5 432718.1
[90,] 415610.0 432720.9
[91,] 415606.2 432716.6
[92,] 415603.2 432713.9
[93,] 415601.4 432710.0
[94,] 415580.3 432708.7
[95,] 415545.1 432709.7
[96,] 415543.5 432711.5
[97,] 415534.0 432715.7
[98,] 415527.1 432713.7
[99,] 415521.1 432711.6
[100,] 415505.6 432710.6
[101,] 415501.3 432710.9
[102,] 415499.3 432708.7
[103,] 415495.6 432711.6
[104,] 415482.6 432726.2
[105,] 415477.2 432734.0
[106,] 415478.1 432737.7
[107,] 415479.2 432739.7
[108,] 415480.9 432743.4
[109,] 415486.5 432751.2
[110,] 415493.2 432760.7
[111,] 415494.1 432762.7
[112,] 415498.1 432767.9
[113,] 415497.2 432770.7
[114,] 415490.6 432773.2
[115,] 415493.2 432775.6
[116,] 415496.0 432778.7
[117,] 415499.2 432779.7
[118,] 415499.6 432781.2
Slot "plotOrder":
[1] 1
Slot "labpt":
[1] 415587.3 432779.4
Slot "ID":
[1] "1"
Slot "area":
[1] 20712.98
Extracting slots
> bdryData@polygons[[2]]@ID
[1] "1"
> bdryData@polygons[[2]]@plotOrder
[1] 1
But problem with coordinates
> bdryData@polygons[[2]]@coords
Error: no slot of name "coords" for this object of class "Polygons"
Any help is really appreciated. Thanks.
Answer
Finally, I figured out that I didn't parse the output correctly. The correct way to do is bdryData@polygons[[2]]@Polygons[[1]]@coords. Mind the difference in command polygons(Polygons and polygons) and it took me ages to find out.