Hfrhyu

My goal is to find neighbors from my SpatialPolygons object using the poly2nb() command from the sp package in R.

This is my code thus far:

 p <- s_gis %>%
 select(long, lat) %>%
 Polygon()
 ps <- Polygons(list(p), 1000)
 sps <- SpatialPolygons(list(ps))

where s_gis is my dataset. I'm otherwise able to make a successful SpatialPolygons object except for the fact that the slot for plotOrder reads 1, instead of 636353 like it is in my dataset.

Running the poly2nb() commands returns an error Error in sp$mbxv[i]:(n * 2) : argument of length 0 which I'm assuming is coming from the fact that it's finding 0 neighbors given that I only have a plotOrder of 1.

How do I modify the plotOrder?

In addition, regarding my error message from the poly2nb() command, if the problem runs deeper, can someone shed some insight as to why?

I have also tried ps@plotOrder <- s_gis$order to no avail.

EDIT:

#get lat, long, and groupid
s_gis_latlon <- s_gis %>%
 select(long,lat, group)

#group lists by group id
p_groups <- split(s_gis_latlon, s_gis_latlon$group)

#delete group id so that we can have 2-column matrix for Polygon
p_groups1 <- lapply(p_groups, function(x) x[,3] <- NULL; x )

# turn each element of list into a polygon
p_groups1 <- lapply(names(p_groups1),
 function(x) b <- Polygon(p_groups1[[x]])
 b
 ) 

#turn list of polygons into Polygons
ps <- Polygons(p_groups1,1)

data <- s_gis %>%
 group_by(group) %>%
 summarize(district_wealthrange = mean(wealthrange))

#create SpatialPolygons object
sps <- SpatialPolygons(ps@Polygons)

I'm getting the error Error in SpatialPolygons(ps@Polygons) :
no slot of name "Polygons" for this object of class "Polygon"

Now we know enough to reproduce your error message, I'll do that with a data frame of lat-long numbers:

> library(sp)
> s_gis = data.frame(long=runif(5), lat=runif(5))

that should be equivalent to your s_gis with lat-long selected. Continue with your code to make sps:

> p = Polygon(s_gis)
> ps = Polygons(list(p), 1000)
> sps = SpatialPolygons(list(ps))

and now use the spdep package:

> library(spdep)
Loading required package: Matrix
> poly2nb(sps, queen=FALSE)
Error in sp$mbxv[i]:(n * 2) : argument of length 0
> 

and there's your error.

poly2nb computes the adjacency matrix between polygons. How many polygons have you got?

> length(sps)
[1] 1
> plot(sps)

One! (although it looks a bit like two but that's because the random lines cross over. This is one ring). No wonder it failed! This data is simply a set of point coordinates in each row - how do you think this data frame could define more than one polygon?