Removing attribute from SpatialPointsDataFrame with spdplyr::select() in R

Question

I'm trying to drop columns/attributes from a SpatialPointsDataFrame, using spdplyr, like so:

library(sp)
library(spdplyr)
x <- c(15.2, 15.3, 15.4, 15.5, 15.7)
y <- c(50.4, 50.2, 50.3, 50.1, 50.4)
v1 <- c(1.0, 2.0, 3.0, 4.0, 5.0)
v2 <- c("a","b","b","c","a")
attributes <- as.data.frame(cbind(v1,v2))
xy <- cbind(x,y)
locationsDD <- SpatialPointsDataFrame(xy, attributes)
locationsDD <- select(locationsDD, -v2)

With the result

Error in `[.data.frame`(x@data, i, j, ..., drop = FALSE) : 
 undefined columns selected

With SpatialPolygonsDataFrames this method works without issues. Is this a bug, or am I doing something wrong?

• mdsumner: Erp, no it looks like a use-case the author of spdplyr did not test. :[
• eivindhammers: Thanks. I see you have commited a fix. I realize my question may have been better suited as a GitHub issue.
• mdsumner: No problem, feel free to do that in future.

Answer 1

The problem is that the internal method doesn't apply drop = FALSE in the subset.

You can install from Github if you want the fix:

devtools::install_github("mdsumner/spdplyr")

But, I recommend moving to sf it's much better all round, and no need for spdplyr any more. Here's the code I would use (I've decided not to have auto-factor-creation):

library(sf)
locationsDD <- st_as_sf(data.frame(x = c(15.2, 15.3, 15.4, 15.5, 15.7), y = c(50.4, 50.2, 50.3, 50.1, 50.4), 
 v1 = c(1.0, 2.0, 3.0, 4.0, 5.0), v2 = c("a","b","b","c","a"), stringsAsFactors = FALSE), 
 coords = c("x", "y"))
library(dplyr)
select(locationsDD, -v2)

• eivindhammers: Thanks. I am in the process of migrating to sf, but I find myself switching back to sp from time to time, since I can't always find sf functions to fulfill all the needs of my workflow (or there are too many lines of code to do what sp-packages can do with one line).
• mdsumner: True enough, but it's still probably better (probably...) to use sf upfront and only go to Spatial when you need to, the round-trip is easy with as(x_sf, "Spatial") and st_as_sf(x_Spatial). Also worth asking on the Github sites (edzer/sfr) and (r-spatial/discuss) for general queries.