R load shapefile: "Error in plot.window(...) : need finite 'ylim' values" - r

Question

I've created the following script to get the coastline of Denmark
# Get Shapefiles for Coastline
shpurl <- "http://download.geofabrik.de/europe/denmark-latest.shp.zip"
tmp <- tempfile(fileext=".zip")
download.file(shpurl, destfile = tmp)
files <- unzip(tmp, exdir=getwd())
# Load & plot shapefile
library(maptools)
shp <- readShapePoly(files[grep(".shp$", shpurl)])
plot(shp)
This should give me the outline of Denmark, however, I keep getting the following error:
Error in plot.window(...) : need finite 'ylim' values
In addition: Warning messages:
1: In xy.coords(x, y, xlabel, ylabel, log) : NAs introduced by coercion
2: In min(x) : no non-missing arguments to min; returning Inf
3: In max(x) : no non-missing arguments to max; returning -Inf
Any help or directions is appreciated.

Answer 1

Have a look at your files value:
> length(files)
[1] 41
The files you are downloading have number of shape files for various geographies. For instance the code:
require(rgdal)
shp <- readOGR(dsn = "whereIsavedyourStuff/Stacks", layer = "roads")
will execute properly. But you will need to specify, which of the sourced shape files you want to read.
As a side point, with respect to reading files from the net, I would suggest that you have a look at this code:
# Download an read US state shapefiles
tmp_shps <- tempfile(); tmp_dir <- tempdir()
download.file("http://www2.census.gov/geo/tiger/GENZ2014/shp/cb_2014_us_state_20m.zip",
tmp_shps)
unzip(tmp_shps, exdir = tmp_dir)
# Libs
require(rgdal)
# Read
us_shps <- readOGR(dsn = tmp_dir, layer = "cb_2014_us_state_20m")
Irrespectively, of what method to read shape files you decide to use you have to specify path and file name. In terms of the provided code in readOGR this is fulfilled by dns and layer options. In your code you used files[grep(".shp$", shpurl)], file names within your 195MB archive, do not corresponds to the URL. You have a few options here:
You can download this files and unpack as you did, list names of all the files that are *.shp, take the file names and pass them in the loop to a list where you would read all combinations (in effect you need a number of files to read each layer)
Better, specify the layer you want to read similarly to the code provided above.