I saw a similar question to the one I have in mind but the solution did not work for me so would like to post here for your help.
I am doing an exercise based on a DataCamp course on geospatial data. The below is the code I executed as a start:
library(sp)
library(tigris)
nyc_tracts <- tracts(state="NY",county="New York", cb=TRUE)
nyc_tracts is created as "spatialpolygonsdataframe" object
I tried to look at the first polygon in the list, with the following syntax:
nyc_tracts@polygons[[1]],
it displays the following:
An object of class "Polygons"
Slot "Polygons":
[[1]]
An object of class "Polygon"
Slot "labpt":
[1] -73.98733 40.71516
Slot "area":
[1] 9.884812e-06
Slot "hole":
[1] FALSE
Slot "ringDir":
[1] 1
Slot "coords":
[,1] [,2]
[1,] -73.98975 40.71555
[2,] -73.98915 40.71671
[3,] -73.98837 40.71645
[4,] -73.98672 40.71595
[5,] -73.98501 40.71544
[6,] -73.98426 40.71521
[7,] -73.98334 40.71493
[8,] -73.98245 40.71470
[9,] -73.98471 40.71451
[10,] -73.98534 40.71446
[11,] -73.98716 40.71431
[12,] -73.98934 40.71413
[13,] -73.99022 40.71440
[14,] -73.98975 40.71555
Slot "plotOrder":
[1] 1
Slot "labpt":
[1] -73.98733 40.71516
Slot "ID":
[1] "156"
Slot "area":
[1] 9.884812e-06
Next, I tried to display slot "area", slot "ID" and slot "plotOrder" etc with commands like the below and they all worked, e.g.
nyc_tracts@polygons[[1]]@area
displays:
[1] 9.884812e-06
However, I cannot get the slot "coord" to work with the same syntax (it seems to be a matrix of 14x2 as shown in the output above), I tried different combinations but they don't work and R gives an error:
nyc_tracts@polygons[[1]]@coords
nyc_tracts@polygons[[1]]@coords[1,1]
error: no slot of name "coords" for this object of class "Polygons"
I also tried using this:
coordinates(nyc_tracts)
but this is not correct, although it does not give an error; it seems to give a list of coordinates from the slot "labpt" from all polygons of the 1nyc_tracts object, and not only the coordinates of the one polygon[[1]] (as displayed above, with 14 rows and 2 columns) I would like to see on my screen.
I am sure there is a very easy solution but I cannot find it. Thanks a lot for your help!!